*2>G- 

>  ^s 


THE   MORPHOLOGY,   DEVELOPMENT   AND 

ECONOMIC  ASPECTS  OF  SCHIZOPHYLLUM 

COMMUNE  FRIES 


BY 


FREDERICK  MONROE  ESSIG 

I 


A  THESIS  ACCEPTED  IN  PARTIAL  SATISFACTION  OF 
THE  REQUIREMENTS  FOR  THE  DEGREE  OF 

DOCTOR  OF  PHILOSOPHY 
^  THE  UNIVERSITY  OF  CALIFORNIA 


1920 


UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS 
IN 

BOTANY 

Vol.  7,  No.  14,  pp.  447-498,  plates  5 1-61  August  11,  1922 


THE   MORPHOLOGY,  DEVELOPMENT,  AND 

ECONOMIC  ASPECTS  OF  SCHIZOPHYLLUM 

COMMUNE  FRIES 


BY 
FREDERICK  MONROE  ESSIG 


UNIVERSITY  OF  CALIFORNIA  PRESS 
BERKELEY,  CALIFORNIA 


UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS 

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WILLIAM  WESLEY  &  SONS,  LONDON 

Agent  for  the  series  in  American  Archaeology  and  Ethnology,  Botany,  Geology, 
Physiology,  and  Zoology. 

BOTANY.— W.  A.  Setchell,  Editor.  Price  per  volume,  $3.50  (vol.  5,  $6.00) ;  beginning  with 
volume  6,  $5.00.  Volumes  I,  n,  HI,  IV,  V,  VI,  VII,  and  IX  completed.  Volumes 
VIH,  X,  and  XI  in  progress. 

Cited  as  Univ.  Calif.  Publ.  Bot. 
VoL  5.     1912-1922. 

1.  Studies  in  Nicotiana.    I,  by  William  Albert  Setchell.    Pp.  1-86.    December, 

1912 _ „ $1.25 

2.  Quantitative  Studies  of  Inheritance  In  Nicotiana  Hybrids.    I,  by  Thomas 

Harper  Goodspeed.    Pp.  87-168,  plates  1-28.    December,  1912 1.00 

3.  Quantitative  Studies  of  Inheritance  in  Nicotiana  Hybrids.    II,  by  Thomas 

Harper  Goodspeed.    Pp.  169-188,  plates  29-34.    January,  1913 20 

4.  On  the  Partial  Sterility  of  Nicotiana  Hybrids  made  with  N.  sylvestris  as  a 

Parent,  by  Thomas  Harper  Goodspeed.    Pp.  189-198.    March,  1913 10 

6.  Notes  on  the  Germination  of  Tobacco  Seed.    I,  by  Thomas  Harper  Good- 
speed.    Pp.  199-222.    May,  1913  - ., 25 

6.  Quantitative  Studies  of  Inheritance  in  Nicotiana  Hybrids,    in,  by  Thomas 

Harper  Goodspeed.    Pp.  223-231.    April,  1915  10 

7.  Notes  on  the  Germination  of  Tobacco  Seed.    II,  by  Thomas  Harper  Good- 

speed.    Pp.  233-248.    June,  1915  _ _ 15 

8.  Parthenogenesis,  Parthenocarpy  and  Phenospermy  in  Nicotiana,  by  Thomas 

Harper  Goodspeed.    Pp.  249-272,  plate  35.    July,  1915 —      .25 

9.  On  the  Partial  Sterility  of  Nicotiana  Hybrids  made  with  N.  sylvestris  as  a 

Parent.  II,  by  T.  H.  Goodspeed  and  A.  H.  Ayres.  Pp.  273-292,  plate  36. 
October,  1916  _ 20 

10.  On  the  Partial  Sterility  of  Nicotiana  Hybrids  made  with  N.  sylvestris  as  a 

Parent,  in,  An  Account  of  the  Mode  of  Floral  Abscission  in  the  F,  Species 
Hybrids,  by  T.  H.  Goodspeed  and  J.  N.  Kendall.  Pp.  293-299.  November, 
1916  v - 05 

11.  The  Nature  of  the  F,  Species  Hybrids  between  Nicotiana  sylvestris  and 

Varieties  of  Nicotiana  Tabacum,  with  Special  Reference  to  the  Conception 
of  Reaction  System  Contrasts  in  Heredity,  by  T.  H.  Goodspeed  and  E.  E. 
Clausen.  Pp.  801-346,  plates  37-48.  January,  1917 45 

12.  Abscission  of  Flowers  and  Fruits  in  the  Solanaceae,  with  Special  Reference 

to  Nicotiana,  by  John  N.  Kendall.    Pp.  347-428,  10  text  figures,  plates  49- 

53.    March,  1918  _ 85 

13.  Controlled  Pollination  in  Nicotiana,  by  Thomas  Harper  Goodspeed  and  Pirie 

Davidson.  Pp.  429-434.    August,  1918  .10 

14.  An  Apparatus  for  Flower  Measurement,  by  T.  H.  Goodspeed  and  R.  E. 

Clausen.    Pp.  435-437,  plat*  54,  1  figure  in  text.    September,  1918  05 

15.  Note  on  the  Effects  of  Illuminating  Gas  and  Its  Constituents  in  Causing 

Abscission  of  Flowers  in  Nicotiana  and  Citrus,  by  T.  H.  Goodspeed,  J.  M. 
McGee  and  R.  W.  Hodgson.  Pp.  439-450.  December,  1918  — _ J.O 

16.  Notes  on  the  Germination  of  Tobacco  Seed,    m,  Note  on  the  Relation  of 

Light  and  Darkness  to  Germination,  by  T.  Harper  Goodspeed.    Pp.  451- 

455.     April,  1919  _ _ -. - - 05 

17.  Inheritance  in  Nicotiana  Tabacum.    I,  A  Report  on  the  Results  of  Crossing 

Certain  Varieties,  by  William  Albert  Setchell,  Thomas  Harper  Goodspeed, 
and  Roy  EVwood  Clausen.  Pp.  457-582,  2  figures  in  text,  plates  55-85. 
April,  1922  1.75 


THE  MORPHOLOGY,  DEVELOPMENT  AND  ECONOMIC  ASPECTS  OF 
SCHIZOPHYLLUM  COMMUNE  FRIES 


A  Thesis  in  Partial  Fulfillment  of  the  Requirements 
for  the  Degree  of  Doctor  of  Philosophy  in  the 
University  of  California  Presented  in 
Nineteen  Hundred  and  Twenty  by 


Frederick  Monroe  Essig 


.'  *  ^* » ••  '  * 

I.;"" 


UNIVERSITY    OF  CALIFORNIA    PUBLICATIONS 

IN 

BOTANY 

Vol.  7,  No.  14,  pp.  447-498,  plates  51-61  August  II,  1922 


THE  MORPHOLOGY,   DEVELOPMENT,  AND 

ECONOMIC  ASPECTS  OF  SCHIZOPHYLLUM 

COMMUNE   FRIES 


BY 

FEEDERICK  MONROE  ES8IG 


CONTENTS 

PAGE 

I.     Introduction 448 

II.     Material  and  Technique 449 

III.  Morphology 451 

1.  General  characteristics  of  the  sporophores 451 

2.  Description  of  the  mature  sporophore 453 

3.  Microscopic  structure 454 

IV.  Growth  of  the  sporophore 458 

1.  Development  in  general 458 

2.  Origin  and  development  of  the  "gills" 461 

3.  Taxonomic  interpretation  of  the  structure  and  development  of 

the  sporophores 463 

V.     Economic  aspects 464 

1.  Geographical  distribution 464 

2.  List  of  host  plants 465 

3.  Extreme  hardiness  of  the  fungus 466 

4.  Relation  of  the  mycelium  to  cells  of  dead  wood 467 

5.  Growths  upon  fresh  wood  and  living  trees 468 

6.  Methods  of  infection  under  natural  conditions 470 

7.  Association  with  other  wood  decay  fungi 471 

VI.     Summary  and  conclusion 472 

VII.     Acknowledgments 473 

Literature  cited 473 

Explanation  of  plates 478 


485474 


448  University  of  California  Publications  in  Botany         [VOL.  7 


I.  INTRODUCTION 

The  peculiar  split  character  of  the  gills  of  Schizophyllum  called 
the  attention  of  botanists  to  this  genus  in  comparatively  early  times. 
Mention  of  this  fungus 'appeared  in  Dillenius'  "Catalogus  plantarum 
sponte  circa  Gissam  nascentium"  more  than  200  years  ago.  Since 
that  time  (1719)  it  has  been  frequently  collected  and  described,  and 
in  the  last  quarter-century  has  been  reported  to  be  of  considerable 
economic  importance,  but  the  literature  upon  the  common  Schizo- 
phyllum is  singularly  fragmentary  and  incomplete.  Early  mention 
was  in  the  form  of  collection  notes  or  brief  descriptions  of  the  dried 
sporophores.  Many  of  these  appeared  in  print  between  the  time  of 
Dillenius  and  the  latter  part  of  the  19th  century. 

In  1884  W.  G.  Smith  found  Schizophyllum  growing  upon  ensilage. 
This  is  the  earliest  mention  of  its  economic  importance  in  available 
literature.  Since  this  article  appeared  Schizophyllum  has  been 
reported  as  parasitic  upon  a  large  variety  of  hosts,  but  papers  relating 
to  the  exact  nature  of  the  parasitism  are  not  to  be  found. 

There  is  also  very  little  published  concerning  the  microscopic  struc- 
ture of  the  sporophores  or  vegetative  hyphae.  A  few  sentences  and 
one  figure  in  Duller 's  "Researches  on  Fungi"  (1909)  give  an  inkling 
as  to  the  structure  of  the  hymenium  and  hyphae  composing  the  gills. 
No  mention  or  illustration  of  contained  protoplasmic  structure  has 
been  found.  Rumbold  (1910)  described  and  featured  the  walls  of 
the  vegetative  hyphae,  but  did  not  mention  the  cell  contents. 

The  literature  upon  the  morphology  of  the  sporophores,  however, 
is  much  more  complete  than  that  upon  the  microscopic  structure. 
Early  descriptions  were  mostly  confined  to  the  structure  of  desiccated 
specimens.  Hasselbring  in  1907  called  attention  to  the  development 
of  the  sporophores  and  the  peculiar  relationship  of  the  hymenophore 
to  the  pileus  and  stipe.  Buller  (1909)  gave  a  full  description  of  the 
mature  sporophores,  origin  of  the  secondary  lamellae,  marginal  split- 
ting, and  incurving  of  the  lamellar  plates.  Adams  (1918)  described 
the  origin  and  development  of  the  lamellae.  The  phenomena  he 
describes,  however,  do  not  agree  with  the  phenomena  displayed  by 
sporophores  growing  in  their  normal  habitat  on  the  University  of 
California  campus. 


1922]       Essig:  Morphology  of  Schizophyllum  commune  Fries          449 

This  paper  is  presented  in  an  effort  to  give  a  more  accurate  and 
complete  description  of  the  sporophores;  a  description  of  the  micro- 
scopic structure  of  the  hyphae  which  go  to  make  up  the  sporophores 
and  the  vegetative  mycelium ;  an  account  of  the  origin  and  develop- 
ment of  the  gills  as  found  in  specimens  growing  in  the  field  at  Berkeley, 
California ;  and  a  report  on  the  economic  aspects  of  the  fungus. 

According  to  Saccardo  (1887-1895),  there  are  twelve  species  of 
Schizophyllum,  all  of  them  being  tropical  or  subtropical  except  S. 
commune  Fries,  which  is  distributed  throughout  the  northern  and 
southern  temperate  zones.  Hennings  (1898)  stated  that  all  of  the 
twelve  forms  described  probably  constituted  only  two  or  three  distinct 
species,  and  this  view  seems  to  the  writer  to  be  more  nearly  correct. 
The  original  work  reported  in  this  paper  is  confined  entirely  to  Schizo- 
pin/thim  commune  Pries,1  but  in  the  table  of  geographical  distribution 
and  the  list  of  host  plants  reference  is  made  to  the  genus  as  a  whole, 
as  it  is  extremely  difficult  to  distinguish  between  the  one  species  of  the 
temperate  zones  and  the  several  tropical  species  described. 


II.  MATERIAL  AND  TECHNIQUE 

The  sporophores  studied  came  from  three  sources: 

1.  Decayed  wood  in  the  field. 

2.  Decayed  wood  kept  in  moist  chambers  in  the  laboratory. 

3.  Specimens  from  the  Herbarium  of  the  University  of  California. 
The  specimens  obtained  from  the  field  were  collected  over  a  period 

extending  from  September,  1917,  to  February,  1920.  They  were 
found  growing  under  natural  conditions  upon  the  wood  or  bark  of 
Acacia  sp.,  Quercus  agrifolia,  and  Umbellularia  calif  arnica.  In  all 
several  hundred  specimens  have  been  collected,  ranging  in  age  from 
apparently  a  few  hours  to  two  years,  and  in  size  from  less  than  1  mm. 
to  5  or  6  cm.  in  diameter.  More  than  a  hundred  specimens  of  very 
young  sporophores  were  obtained  during  the  autumn  of  1919  from  a 
single  log  of  Umbellularia  partly  imbedded  in  gravel  along  a  small 
creek  near  the  laboratory. 

As  an  experiment  short  sections  of  small  trunks  and  branches  of 
trees  infected  with  Schizophyllum  were  placed  in  shallow  pans  of  water 
and  covered  with  bell  jars.  Air  was  admitted  by  supporting  the  bell 


1  For  a  complete  list  of  synonyms  see  Greville  (1824)  antl  Murrill  (1915). 
The  most  important  are  Agaricus  alneus  Linnaeus,  SchizopJtyllum  alneum  Schroeter, 
Schizophyllus  alneus  Murrill. 


450  University  of  California  Publications  in  Botany         [VOL.  7 

jars  so  that  the  lower  edge  did  not  quite  touch  the  surface  of  the  water. 
Under  these  conditions  sporophores  could  be  induced  to  grow  through- 
out the  year,  new  ones  appearing  successively  as  the  mature  specimens 
were  removed.  In  this  way  the  development  of  the  sporophores  could 
be  watched  from  day  to  day  and  compared  with  conditions  found  in 
the  field.  It  might  be  stated  here  that  at  no  time  was  there  any  essen- 
tial difference  between  specimens  found  in  the  field  and  those  grown 
in  moist  chambers  in  the  laboratory.  The  moist  chambers  also  fur- 
nished an  excellent  opportunity  for  the  study  of  regeneration  phe- 
nomena. 

In  the  third  source  of  material,  the  Herbarium  of  the  University 
of  California,  specimens  from  many  localities  in  California  are  pre- 
served, as  well  as  some  from  Whidbey  Island,  Washington ;  from 
Ontario,  Canada;  and  from  France.  These  sporophores  were  used  for 
comparison  with  respect  to  general  morphological  characters. 

In  the  matter  of  technique  no  claim  is  made  for  originality.  It 
was  found  at  the  beginning  of  the  work  that  the  processes  used  in  the 
treatment  of  the  fleshy  fungi  did  not  give  satisfactory  results  when 
applied  to  Schizophyllum.  After  experimenting  with  many  methods 
those  outlined  below  were  found  to  be  the  best  suited  for  use  with  this 
fungus. 

The  killing  and  fixing  agent  used  for  the  young  sporophores  was  a 
70  per  cent  solution  of  alcohol  with  6  c.c.  of  commercial  formalin 
added  to  each  100  c.c.  of  the  alcoholic  solution.  This  not  only  killed 
and  fixed  the  material  but  preserved  it  indefinitely.  Spores  were 
caught  in  a  film  of  albumen  fixative  on  a  slide  and  fixed  in  100  per  cent 
alcohol,  thus  hardening  the  fixative  and  fastening  the  spores  to  the 
slide. 

Most  of  the  sectioning  was  done  on  a  rotary  microtome,  the  material 
being  frozen  in  a  solution  of  gum  arabic  (compare  Gardner,  1917). 
Some  of  the  specimens  were  imbedded  and  sectioned  in  paraffin,  but 
this  method  did  not  give  good  results,  as  the  material  became  hard  and 
difficult  to  section.  The  sporophores  for  the  study  of  early  develop- 
mental stages  were  sectioned  individually,  and  all  the  sections  from  a 
single  specimen  were  preserved  in  a  vial.  From  these  vials  the  sec- 
tions were  poured  into  shallow  dishes  where  all  could  be  seen.  Only 
those  sections  cut  at  or  near  the  median  plane  were  selected  for  mount- 
ing. Albumen  fixative  was  used  to  fasten  the  sections  on  the  slide. 
Great  care  was  used  in  orienting  the  imbedded  sporophores  before 
sectioning,  as  oblique  sections  through  the  revolute  hymenial  margins 


1922]       Essig:  Morphology  of  Schizophyllum  commune  Fries         451 

lead  to  entirely  erroneous  interpretations  of  the  structure  of  the  sporo- 
phore.  Thus  sections  cut  obliquely  through  specimens  with  well  devel- 
oped "gills"  which  can  be  seen  unmistakably  with  the  unaided  eye 
appear  as  though  the  hymenium  lined  a  series  of  chambers,  or  as  if 
the  "gills"  in  the  middle  of  the  section  were  normal,  with  "hymenial 
chambers"  at  each  edge.  Certain  sections  cut  in  this  manner  corre- 
sponded in  many  ways  to  figures  given  by  Adams  (1918).  Material 
for  young  developmental  stages  was  sectioned  from  20  to  25/x  in  thick- 
ness so  that  the  sections  would  remain  entire.  For  cytological  work 
the  sections  were  cut  5  and  10  micra  thick.  Sections  as  thin  as  5  micra 
will  not  hold  together  well,  so  that,  for  the  finer  structure,  it  was  neces- 
sary to  use  only  fragments. 

Plemming's  triple  stain  was  used  for  some  sections,  but  was  not  so 
satisfactory  as  safranin  alone.  Using  a  two-minute  period  in  a  3  per 
cent  solution  of  safranin  in  50  per  cent  alcohol  and  washing  out  rap- 
idly, a  fair  differentiation  was  obtained.  The  nuclei  stain  deep  red, 
the  cytoplasm  a  very  light  pink,  and  the  cell  walls  an  intermediate 
shade.  All  efforts  to  make  the  nuclei  stand  out  more  clearly  by  coun- 
terstaining  resulted  in  failure.  For  staining  spores,  a  48-hour  period 
was  needed,  as  in  a  shorter  period  the  stain  would  be  almost  entirely 
removed  in  the  washing-out  and  dehydrating  operations  preceding 
clearing  and  mounting.  The  sections  and  spores  were  cleared  in  xylol 
and  mounted  in  Canada  balsam. 


III.  MORPHOLOGY 
1.  GENERAL  CHARACTERISTICS  OF  THE  SPOEOPHORES 

Schizophyllum  is  distinctly  a  xerophyte.     The  sporophores  are 
found  in  either  of  two  conditions : 

1.  In  dry  weather  the  sporophores  are  desiccated,  hard,  and  some- 
what brittle  (fig.  1,  pi.  51).  The  margin  of  the  pileus  is  curved  inward, 
decreasing  the  width  of  the  sporophore  about  25  per  cent.     Each 
hymenial  plate  is  incurved  on  the  side  toward  the  hymenium.     The 
hymenial  surface  is  hidden  and  protected.     Only  the  villous  sterile 
surface  of  the  hymenial  plates  can  be  seen  from  the  lower  side.    There 
is  no  discharge  of  spores.    This  is  an  inactive  period. 

2.  In  moist  weather  the  sporophores  take  up  water  and  become 
flexible  and  leathery  in  consistency.    The  pileus  margin  is  only  slightly 
curved  downward.    The  gill  plates  unroll  and  extend  vertically  down- 
ward, or  nearly  so  (fig.  2,  pi.  51).    Spore  discharge  begins  about  an 


452  University  of  California  Publications  in  Botany          [VOL.  7 

hour  after  the  sporophores  are  moistened,  and  continues  for  a  maxi- 
mum period  of  about  two  weeks.  However,  under  natural  conditions 
the  period  is  usually  shorter,  as  the  spores  cease  to  fall  as  soon  as  the 
sporophores  become  dry.  Growth  takes  place,  the  most  actively  grow- 
ing region  being  at  the  pileus  margin  and  at  the  edge  of  each  gill  plate. 
Specimens  are  naturally  most  commonly  collected  when  in  a  dry 
condition. 

The  form  of  the  fruit  bodies  varies  greatly,  depending  in  great 
part  upon  the  position  of  the  surface  of  the  substratum.  Thus  the 
sporophores  growing  upon  the  under  surface  of  a  piece  of  wood  are 
quite  different  in  form  from  those  found  upon  the  upper  surface,  and 
those  growing  from  a  vertical  surface  differ  from  both  of  the  preced- 
ing ;  but  for  every  one  of  these  three  positions  the  form  is  fairly  con- 
stant. 

The  diversity  of  form  is  due  to  the  peculiar  organization  of  the 
sporophore,  the  stipe  being  attached  to  the  upper  surface  of  the  pileus, 
with  the  hymenophore  upon  the  opposite  side  of  the  pileus  away  from 
the  stipe.  Thus  Schizophyllum  differs  from  all  other  stipitate  members 
of  the  Agaricaceae  so  far  studied.  This  difference  was  conclusively 
demonstrated  by  Hasselbring  (1907),  who  grew  the  sporophores  upon 
a  klinostat.  He  showed  that,  when  not  influenced  by  the  force  of 
gravity,  the  stipe  was  always  attached  near  the  center  of  the  pileus, 
but  on  the  opposite  side  from  the  ' '  gills. ' '  This  unusual  organization, 
according  to  De  Bary  (1887),  is  also  possessed  by  Cyphella,  a  member 
of  the  Thellephoraceae. 

The  form  which  Hasselbring  found  is  the  one  assumed  by  fruit 
bodies  growing  in  nature  from  the  under  surface  of  the  substratum. 
There  is  a  stipe,  which  is  usually  short,  attached  to  the  center  of  the 
upper  surface  of  the  pileus.  The  sporophore  is  shaped  like  a  broad 
funnel  or  bell,  the  hymenium  lining  the  inner,  and  also  the  lower,  sur- 
face (fig.  1,  pi.  52).  On  a  vertical  surface  the  form  of  the  sporophores 
depends  in  great  part  upon  the  length  of  the  stipe  (fig.  2,  pi.  52).  If 
this  structure  is  short,  it  is  attached  to  the  pileus  near  the  edge,  and 
the  sporophore  is  ear-shaped.  If  the  stipe  is  long,  it  may  be  curved 
downward  at  the  outer  end  and  be  attached  to  the  pileus  near  the 
center,  as  in  specimens  grown  upon  an  under  surface.  Then  the  shape 
is  that  of  a  curved  trumpet.  In  the  ear-shaped  forms  the  stipe  is  so 
short  that  it  cannot  curve  downward,  so  that  the  upper  edge  of  the 
young  sporophore  is  stimulated  by  gravity  (as  shown  by  Hasselbring) 
to  grow  more  rapidly  than  the  lower  edge.  Thus  the  hymenium  is 


1922]       Essig:  Morphology  of  Schizophyllum  cmmnune  Fries        453 

brought  into  a  more  advantageous  position  for  spore  discharge.  On 
an  upper  surface  the  stipe  is  attached  to  the  pileus  at  the  very  edge 
(fig.  3,  pi.  52).  The  lower  edge  of  the  young  trumpet-shaped  sporo- 
phore  never  develops.  The  gill  plates  radiate  outward  from  a  place 
near  the  attachment  of  the  stipe. 

The  sporophores  are  borne  singly  or  in  groups.  The  groups  may 
contain  from  a  few  to  several  scores  of  specimens  attached  to  each 
other  at  the  base  of  the  stipe.  Sometimes  more  than  one  sporophore 
grows  upon  a  single  stipe,  but  such  an  occurrence  is  rare.  Only  cer- 
tain members  of  a  group  reach  maturity,  a  large  percentage  never 
developing  beyond  a  very  early  stage. 


2.  DESCRIPTION  OF  THE  MATURE  SPOROPHOEE 

The  shape  of  the  individual  sporophore  varies  from  broadly  bell- 
shaped  with  a  centrally  attached  stipe  to  ear-  or  racket-shaped  with 
the  stipe  attached  to  the  edge  of  the  pileus.  The  edge  of  the  pileus 
may  be  entire  or  more  or  less  deeply  lobed.  If  the  lobes  are  large  and 
deep,  they  may  have  secondary  lobing.  The  size  of  the  mature  sporo- 
phores ranges  from  2  mm.  to  5  cm.  in  length  and  from  3  mm.  to  6  cm. 
in  width. 

The  color  of  the  pileus  may  be  silvery  or  velvety  white,  gray,  or 
cream  colored.  The  sterile  surfaces  of  the  hymenial  plates  are  a  dark 
gray  with  often  a  purplish  tint.  The  hymenium  is  a  shiny  brownish- 
gray.  There  is  a  considerable  variation  in  the  color  of  all  parts  of 
the  fruit  bodies,  depending  upon  the  age  and  whether  they  are  wet 
or  dry. 

A  stipe  is  usually,  but  not  always,  present.  Its  presence  and  length 
depend  upon  the  amount  of  moisture  in  the  substratum  and  atmo- 
sphere at  the  early  stages  of  growth,  a  maximum  amount  of  moisture 
inducing  a  greater  growth  in  length.  The  length  varies  from  1  mm. 
to  2  or  3  cm.  The  form  is  cylindrical.  The  stipe  rarely  attains  a 
width  of  more  than  half  a  centimeter. 

The  pileus  is  covered  with  a  dense  mass  of  thick-walled  hyphae. 
If  these  hyphae  are  vertical  and  remain  free  from  each  other,  the 
surface  appears  velvety.  If  they  are  agglutinated  into  groups  at  the 
upper  ends,  the  surface  is  rough  and  scurfy.  If  the  upper  ends  form 
a  horizontal  layer,  the  surface  has  a  silvery  sheen.  The  depth  of  the 
hyphal  covering  varies  from  1.5  to  2.5  mm.  The  pileus  is  made  up 
of  thick-walled,  septate  hyphae.  These  are  closely  packed  together, 


454  University  of  California,  Publications  in  Botany         [VoL-  7 

but  do  not  in  any  case  constitute  a  pseudoparenchymatous  tissue.  The 
upper  layer  of  the  pileus  flesh  is  pigmented  brown. 

The  lamellar  plates  extend  downward  from  the  pileus  (fig.  22,  pi. 
52).  They  are  arranged  in  pairs;  each  pair,  with  the  sterile,  hairy 
surfaces  together,  giving  the  appearance  of  a  lamella.  Each  plate, 
however,  is  independent  of  the  other  to  a  certain  degree,  and  may 
vary  from  it  in  size  and  shape.  A  hymenial  plate  may  attain  a  depth 
of  3  mm.,  the  depth  depending  entirely  upon  the  number  and  length 
of  the  growing  periods  following  the  origin  of  the  plate,  for  growth  is 
continuous  throughout  the  duration  of  favorable  conditions.  Each 
plate  exhibits  a  growth  region  at  the  margin,  which,  after  the  earliest 
stages,  is  continuous  with  and  similar  to  the  margin  of  the  pileus. 
Since  the  plates  arise  successively  in  pairs,  a  great  many  different 
ages  and  sizes  may  be  found  in  the  same  mature  sporophore. 

The  hymenium  either  covers  a  much  divided  single  area  or  is 
separated  into  several  different  areas  in  the  same  sporophore,  as  in 
plate  53.  The  elements  in  the  hymenial  layer  are  closely  crowded 
together,  and  in  old  specimens  tightly  adhere  to  each  other,  so  that 
a  large  area  of  the  hymenium  may  be  removed  from  the  subhymenial 
layer  without  separating  the  basidia  from  one  another. 

3.  MICROSCOPIC  STRUCTURE 

The  study  of  the  microscopic  structure  of  Schizophyllum  presents 
considerable  difficulty.  Upon  dehydration  the  sporophores  become 
hard  and  brittle,  so  that  the  paraffin  method  of  obtaining  sections  is 
impracticable.  When,  by  using  other  methods,  sections  are  obtained, 
it  is  found  that  the  hyphal  walls  are  thick,  the  segments  extremely 
long,  and  that  the  nuclei  are  small  and  difficult  to  differentiate  by 
staining. 

The  vegetative  hyphae  commonly  branch,  but  not  with  great  .fre- 
quency. The  branching  rarely  occurs  at  or  near  a  septum,  but  usually 
takes  place  about  the  middle  of  a  segment  (fig.  1,  pi.  54).  The  hyphae 
are  of  two  sizes,  one  having  a  diameter  of  3  to  5ju,  and  the  other  being 
only  about  1  or  2/t  wide.  The  finer  hyphae  are  particularly  abundant 
when  the  mycelium  is  grown  upon  artificial  media,  but  are  also  found 
to  some  extent  in  wood.  The  hyphae  are  often  covered  with  small 
tubercles,  as  was  described  by  Brefeld  (1889)  in  S.  lobatum  and  Miss 
Rumbold  (1910)  in  8.  commune.  This  seems  to  be  a  distinctive  char- 
acter. The  function  of  these  lateral  projections  (fig.  2,  pi.  54)  is  not 


1922]       Essig:  Morphology  of  Schizophyllurn  commune  Fries        455 

apparent  from  their  structure.  It  is  possible  that  they  aid  in  the 
absorption  of  food  materials,  since  they  closely  resemble  haustoria  in 
shape  and  are  found  only  on  those  hyphae  which  are  purely  vegetative. 
Clamp  connections  (fig.  1,  pi.  54)  are  found  at  more  than  half  of  the 
septa  in  actively  growing  mycelium.  They  have  been  observed  upon 
the  hyphae  of  members  of  the  Hymenomycetes  since  the  earliest  studies 
of  their  cell  structure.  Though  they  occur  in  a  great  number  of  fungi 
in  this  group,  their  exact  function  is  not  understood.  Harper  (1902) 
suggested  that  they  possibly  facilitated  the  exchange  of  food  materials 
between  segments,  but  just  how  this  is  accomplished  is  not  clear.  The 
length  of  the  segments  varies  from  about  30/*  to  more  than  200/t,  the 
usual  length  being  about  80/x.  The  thickness  of  the  wall  varies  from 
about  0.1  to  0.5ft..  In  rapidly  growing  hyphae  there  are  few  vacuoles 
and  these  are  small.  The  protoplasm  is  of  fine  granular  structure  and 
very  homogeneous.  As  the  mycelium  becomes  older  the  vacuoles 
enlarge,  oil  droplets  are  formed,  and  many  of  the  cells  collapse.  There 
are  two  nuclei  to  a  segment  (fig.  1,  pi.  54).  They  are  small  and  spher- 
ical, about  0.3  to  0.5/A  in  diameter.  Their  structure  is  granular.  No 
nucleoli  have  been  seen.  The  nuclei  are  usually  found  about  10  to  20/u 
apart  near  the  center  of  a  segment.  These  compare  very  well  with 
the  nuclei  in  the  vegetative  hyphae  of  Hypochnus  subtilis  (Harper, 
1902,  fig.  1,  pi.  1).  Maire  (1900)  found  but  one  nucleus  in  the  "cells" 
of  the  mycelium  of  Coprinus  radiatus. 

The  hyphae  which  compose  a  sporophore  are  of  several  different 
types.  One  kind  includes  those  which  form  the  hairy  covering  of  the 
pileus  and  sterile  surface  of  the  hymenial  plates;  another  makes  up 
the  pileus  and  tramal  structure,  and  the  third  forms  the  subhymenial 
layer.  Again,  each  of  these  types  varies  somewhat  according  to  the 
age  and  state  of  development  of  the  sporophore. 

The  hyphae  which  cover  the  pileus  and  sterile  surfaces  of  the 
hymenial  plates  are  composed  in  nearly  all  cases  of  but  a  single  seg- 
ment, which  may  be  as  long  as  3  mm.  These  hyphae  are  of  a  fairly 
uniform  size  and  length  (fig.  3,  pi.  54).  They  are  irregularly  curved 
and  tangled  together.  The  walls  are  in  the  younger  stages  fairly  thin, 
but  as  development  proceeds  they  gradually  thicken  until  in  very  old 
specimens  the  lumen  has  almost  entirely  disappeared.  Two  nuclei 
are  present  in  each  hypha  of  the  hairy  covering.  They  are  similar  in 
size  and  shape  to  those  of  the  vegetative  hyphae.  They  are  found 
regularly  near  the  base  of  the  segment. 


456  University  of  California,  Publications  in  Botany          [VOL-  1 

The  filaments  which  constitute  the  solid  portion  of  the  sporophore 
are  in  their  younger  stages  similar  to  the  larger  hyphae  which  make 
up  the  vegetative  mycelium  (fig.  4,  pi.  54).  As  the  fruit  bodies  become 
older  the  segments  lengthen,  and  the  walls  thicken  until  they  are  about 
equal  in  thickness  to  the  width  of  the  lumen  (fig.  5,  pi.  53).  When 
the  microscope  is  focused  up  and  down  upon  thick  sections  cut  trans- 
versely across  the  hyphae  it  is  seen  that  the  filaments  are  loosely 
coiled  in  a  fairly  regular  spiral,  some  turning  clockwise  and  others 
counter-clockwise.  In  old  sporophores  the  hyphae  adhere  tightly  to 
each  other  wherever  they  are  in  contact.  In  the  earlier  thin-walled 
state  the  segments  are  filled  with  cytoplasm  and  have  two  typical, 
small  nuclei.  This  is  precisely  the  situation  found  by  Harper  (1902) 
in  Coprinus  ephemerus  and  Hypochnus  subtilis.  Clamp  connections 
are  numerous,  but  no  spine-like  tubercles  appear.  The  protoplasmic 
contents  of  the  thick-walled  hyphae  of  older  sporophores  are  masked 
by  the  walls  to  such  a  degree  that  the  number  of  nuclei  present  can- 
not be  determined.  In  Coprinus  ephemerus  (Harper,  1902)  there  are 
many  nuclei  in  the  old  "cells"  of  the  pileus  and  stipe.  Maire  (1900) 
found  the  same  to  be  true  in  a  large  number  of  the  fleshy  Agaricaceae 
which  he  had  examined. 

The  subhymenial  layer  is  composed  of  hyphae  which  are  thin- 
walled,  and  which  retain  the  characters  displayed  by  all  the  hyphae 
in  their  earlier  state.  Branching  is  common,  and  clamp  connections 
are  plentiful.  There  are  two  nuclei  to  each  segment.  The  segments 
are  rich  in  cytoplasm. 

The  basidia  are  borne  at  the  ends  of  thin-walled  hyphae.  They 
are  only  slightly  larger  in  diameter  than  the  hyphae  which  bear  them. 
All  the  elements  in  the  hymenium  are  similar  (fig.  6,  pi.  54),  that  is 
there  is  no  distinction  between  potential  basidia  and  paraphyses. 
Mature  basidia  project  beyond  the  hymenial  surface.  The  basidia 
come  to  maturity  in  succession,  only  a  few  in  a  relatively  large  area 
being  found  with  spores  attached  at  any  one  time.  The  basidia  meas- 
ure 5  by  20ju.  Each  has  four  long,  slender  sterigmata  and  bears  four 
spores.  Immature  basidia  display  two  nuclei.  No  fusion  of  these 
nuclei  has  been  observed,  but  in  later  stages  four  have  been  seen.  It 
is  therefore  presumed  that  the  usual  fusion  and  two  successive  divi- 
sions, as  described  by  Wager  (1893),  Maire  (1900),  and  Harper 
(1902),  have  taken  place. 

The  spores  en  masse  are  white.  When  seen  with  the  microscope 
they  are  nearly  hyaline  and  of  an  olive  green  shade.  There  is  a  con- 


1922]       Essig:  Morphology  of  Schizophyllum  commune  Fries        457 

siderable  diiference  of  opinion  in  the  literature  as  regards  the  shape 
and  size  of  the  spores.  The  early  writers,  such  as  Fries  (1821),  Cooke 
(1871),  and  Saccardo  (1887),  stated  that  they  were  subglobose,  about 
2.5/i  in  diameter.  Morgan  (1890)  called  attention  to  the  fact  that 
the  spores  he  had  been  examining  averaged  5-6  by  2.5/x,  and  won- 
dered if  a  mistake  had  been  made,  or  if  his  were  possibly  a  different 
species.  The  possibility  of  a  different  species  seems  unlikely,  for  later 
Hennings  (1898)  and  Rumbold  (1910)  in  Europe  and  Murrill  (1915) 
in  America  have  found  them  to  be  oblong,  at  least  twice  as  long  as 
broad.  It  is  possible  that  the  globular  bodies  supposed  by  the  early 
writers  to  be  spores  were  nothing  but  the  peculiar  structures  which 
are  shed  by  the  dried  sporophores  when  first  they  are  wetted  to  obtain 
a  spore  print.  These  bodies  and  no  spores  are  dropped  by  old  her- 
barium specimens,  which  have  lost  their  vitality,  when  they  are  mois- 
tened. The  spores  occasionally  possess  small  vacuoles.  No  oil  drop- 
lets have  been  demonstrated.  The  wall  is  thin.  The  spores  are  densely 
filled  with  protoplasm.  At  shedding  time  two  nuclei  are  present 
(fig.  7,  pi.  54). 

The  number  of  nuclei  in  the  spores  of  the  Hymenomycetes  so  far 
examined  is  either  one  or  two.  One  was  found  in  the  spore  of  Hypoch- 
nus  subtilis  (Harper,  1902),  Amanita  vaginata,  Tricholoma  virgatum, 
and  Cantharettus  infundibuliformis  (Rosenvinge,  1886),  while  two 
were  found  in  Craterellus  cornucopioidcs,  Clavaria  vermicularis,  Bole- 
tus edulis,  and  B.  variegatus  (Rosenvinge,  1886).  Maire  (1900),  after 
studying  some  thirty  species,  stated  that  there  might  be  either  one  or 
two  nuclei  in  a  spore.  In  the  case  of  two  nuclei,  the  single  nucleus 
divides  as  soon  as  it  enters  the  spore  from  the  basidium,  instead  of 
just  preceding  the  first  segmentation  during  spore  germination. 

Spores  germinate  readily  in  water  and  in  a  great  variety  of  culture 
media.  The  spores  first  swell  to  nearly  twice  the  normal  size ;  then  a 
germ  tube  appears  at  either  one  or  both  ends  (fig.  8,  pi.  54).  The 
width  of  the  germ  tube  often  approximates  that  of  the  spore,  and  as 
a  result  the  identity  of  the  spore  may  soon  be  lost.  The  length  that 
the  tube  attains  prior  to  segmentation  depends  to  a  certain  extent 
upon  the  nature  of  the  culture  medium,  segmentation  occurring  earlier 
when  the  medium  is  rich  in  food  materials.  In  tap  water  growth 
ceases  about  the  time  the  first  septum  and  branch  appear.  Branching 
may  occur  either  before  or  after  the  first  septum  is  laid  down,  but  it 
usually  occurs  about  that  time. 


458  University  of  California  Publications  in  Botany         [VOL.  7 


IV.  GROWTH  OP  THE  SPOEOPHORE 

1.  DEVELOPMENT  IN  GENERAL 

The  development  of  the  sporophores  was  early  looked  to  for  an 
explanation  of  the  peculiar  pairs  of  hymenial  plates  which  charac- 
terize Scliizophyllum.  Fries  (1821)  believed  that  they  arose  as  ordi- 
nary gills  and  were  split  by  drying.  This  view  was  again  brought 
forward  by  Fayod  (1889),  and  still  later  by  Buller  (1909).  Hoffman 
(1860)  believed  the  sporophore  to  be  divided  into  a  series  of  lamellar 
systems,  considering  all  the  secondary  gills  to  belong  to  the  primary 
hymenial  plates  which  enclosed  them.  His  view  was  adopted  by  Winter 
(1884). 

Adams  recently  (1918)  made  the  statement  that  each  lamella  con- 
sists "of  the  adjacent  walls  of  two  gill  cavities  which  originate  endo-- 
genously  as  tubes  in  the  substance  of  the  carpophore.  The  gill  cavities 
(tubes)  split  along  their  lower  edges  and  lamellae  are  thus  completed." 

In  Hasselbring's  (1907)  paper  on  "Gravity  as  a  Form-Stimulus 
in  Fungi"  appears  the  statement  that  "they  [the  young  sporophores 
of  8.  commune]  appear  as  small  outgrowths  resembling  simple  forms 
of  Clavaria,  and  attain  a  length  of  about  one  centimeter.  Early  in 
their  development  a  cup-like  depression  appears  at  the  summit,  and 
within  this  the  rudimentary  lamellae  are  formed,  radiating  from  the 
center." 

Two  distinctly  opposed  views  have,  then,  been  advanced  by  Hassel- 
bring  and  Adams.  Adams  held  that  the  "gills"  originated  endogen- 
ously  as  the  sides  of  horizontal  tubes  which  later  ruptured  at  the 
lower  edge  and  exposed  the  hymenium,  while  Hasselbring  claimed  that 
the  "gills"  arose  exogenously  upon  the  surface  of  an  apical  cup-like 
depression.  It  seems  unlikely  that  Buller  and  the  previous  writers 
had  access  to  sporophores  in  the  first  stages  of  development,  for  they 
made  no  statements  concerning  the  early  appearance  of  the  fruit 
bodies.  Both  Adams  and  Hasselbring,  however,  grew  the  sporophores 
through  all  their  stages  in  the  laboratory.  Adams  grew  his  in  flasks 
on  agar  media  from  "immature  carpophores  collected  in  the  field." 
Hasselbring  caused  them  to  grow  from  ' '  pieces  of  a  maple  branch  con- 
taining the  mycelium — placed  on  a  klinostat. " 

The  writer  has  had  an  opportunity  to  study  the  origin  and  devel- 
opment of  the  sporophores  both  on  a  log  of  Umbellularia  caUfornica 


1922]       Essig:  Morphology  of  Schizophyllum  commune  Fries        459 

(California  Bay)  in  the  field  near  the  laboratory  where  more  than 
a  hundred  sporophores  have  grown  during  the  autumn  and  winter  of 
1919-1920 ;  and  in  the  laboratory  where  scores  of  sporophores  have 
appeared  upon  the  wood  of  Acacia,,  Quercus,  and  Umbellularia  in  moist 
chambers.  Dozens  of  the  fruit  bodies  have  been  sectioned,  either  longi- 
tudinally or  transversely. 

No  phenomena  in  the  course  of  the  development  of  the  sporophores 
have  been  observed  that  in  any  way  approximated  those  described  by 
Adams  (1918)  for  Schizophyllum  commune.  By  cutting  oblique  sec- 
tions through  small  mature  specimens  his  figures  2  to  7  in  plate  9 
may  be  imitated  with  fair  accuracy,  but  these  sections  cannot  permit 
of  such  an  interpretation  as  he  has  given  for  his  sections.  The  crena- 
tures  which  he  shows  in  figures  2  to  5,  plate  9,  are  entirely  absent  in 
all  of  the  160  or  more  young  specimens  the  writer  has  examined.  The 
sporophores  which  grew  here  in  the  laboratory  and  in  the  field  devel- 
oped much  as  was  described  by  Hasselbring  (1907). 

The  fruit  bodies  appear  first  as  small,  loose  tufts  on  the  substratum. 
These  develop  into  small  white  woolly  projections  either  short  and 
hemispherical  or  prolonged  into  horn-like  structures,  "resembling 
simple  forms  of  Clavaria"  (fig.  2,  pi.  56).  The  end  is  either  rounded 
or  conical.  These  small  bodies  are  covered  with  loose  tangled  hyphae. 
Later  the  apex  becomes  smooth,  slightly  darker  in  color,  and  covered 
with  shorter  hyphae. 

Next  a  single  pore  appears  at  the  apex  (fig.  3,  pi.  56),  as  Hassel- 
bring (1907)  found.  Early  stages  which  show  the  origin  of  this  pore 
have  been  difficult  to  distinguish,  as  it  develops  within  a  few  hours 
after  the  formation  of  the  buttons  or  horns,  and  the  loose  hairs  at  the 
apex  screen  its  first  appearance.  Longitudinal  sections  at  this  stage 
show  first  a  differentiation  of  the  hyphae  just  behind  the  apex  (fig.  1, 
pi.  59).  This  region  stains  more  deeply  than  the  remainder  of  the 
section.  The  growth  at  this  place  is  accelerated,  and,  as  increase  in 
size  takes  place  behind  the  apex,  the  hyphae  at  the  tip  are  pulled  apart 
(fig.  2,  pi.  59).  The  hyphae  beneath  the  rupture  form  a  palisade  layer 
which  extends  laterally  into  a  plane  surface  (fig.  3,  pi.  59).  The 
growth  then  becomes  more  rapid  at  the  edge  of  the  layer,  producing 
it  outward  into  a  saucer-shaped  and  later  a  cup-shaped  depression. 
In  this  stage  it  resembles  a  small  sporophore  of  a  Peziza  (fig.  4, 
pi.  59). 

In  all  cases  observed  by  the  writer  the  so-called  lamellae  have 
originated  upon  the  surface  of  this  apical  cavity  (figs.  4—14,  pi.  52), 


460  University  of  California  Publications  in  Botany         [VOL-  7 

which  surface  constitutes  the  hyraenium  primordium.  This  is  exactly 
as  described  by  Hasselbring  (1907),  but  he  did  not  go  into  detail 
concerning  the  placement  or  development  of  the  hyraenial  plates. 
The  pore  attains  a  width  of  from  1.5  to  2  mm.  before  the  appearance 
of  the  first  pair  of  plates.  Dozens  of  specimens  in  the  ' '  apical  depres- 
sion" or  "peziza"  stage  have  been  observed  where  there  was  no  indi- 
cation of  lamellae.  By  splitting  the  specimen  in  half  longitudinally 
the  entire  surface  of  the  hymenium  primordium  may  be  examined 
with  a  hand  lens.  Microscopical  examination  of  prepared  sections 
fails  to  disclose  any  indication  of  closed  chambers  or  of  "  gills ' '  before 
the  "lamellae"  are  plainly  visible  upon  the  surface  of  the  hymenium 
primordium. 

The  placement  of  the  "gills"  may  be  easily  observed  in  actively 
growing  moist  specimens  (figs.  4—14,  pi.  52).  They  arise  as  short, 
isolated  ridges  upon  the  surface  of  the  hymenium  primordium.  The 
primary  ridges  arise  successively  from  a  point  beneath  the  attachment  • 
of  the  stipe,  and  grow  outward  in  a  radial  direction  until  they  finally 
unite  with  the  edge  of  the  pileus.  The  secondary  "gills"  originate 
between  the  gills  already  developed,  but  do  not  extend  so  near  to  the 
stipe  as  do  those  already  formed.  They  occupy,  as  Buller  (1909) 
noted,  an  isolated,  subterminal  position  within  the  interlamellar  space 
in  which  they  have  been  formed.  As  growth  proceeds,  however,  the 
distal  ends  gradually  approach  the  pileus  margin  and  eventually  unite 
with  it,  as  do  the  primary  ridges. 

Soon  after  a  "gill"  imites  with  the  pileus  margin,  the  pileus 
becomes  split  in  from  the  edge,  though  often  this  is  not  disclosed 
upon  the  dorsal  surface  because  of  the  hyphal  covering.  This  mar- 
ginal splitting  is  doubtless  to  some  extent  hygroscopic,  as  specimens 
kept  moist  from  the  first  are  split  only  slightly,  while  those  subjected 
to  alternate  wetting  and  drying  are  split  farther  toward  the  stipe  ends 
of  the  ' '  gills, ' '  dividing  the  pileus  as  well  as  the  hymenium  into  narrow 
finger-like  projections,  the  crenatures  of  Buller  (1909). 

Occasionally  there  is  an  unusual  placement  of  certain  "gills." 
Sometimes  they  arise  at  an  angle  to  the  radial  direction.  In  this  case 
they  frequently  remain  short  and  isolated.  Often  there  is  a  consider- 
able sterile  area  between  the  two  hymenial  plates  (fig.  1,  pi.  60).  This 
is  very  commonly  found  at  the  stipe  end  of  "gills"  in  lateral  sporo- 
phores.  Rarely  the  first  few  primary  gills  formed  unite  with  each 
other  and  the  pileus  margin  to  divide  the  hymenium  primordium  into 
several  separate  areas,  in  which  the  secondary  "gills"  later  are  formed 
(fig.  15,  pi.  52). 


1922]       Essig:  Morphology  of  Schizophyllum  commune  Fries        461 

Upon  a  superficial  examination  the  "gills"  appear  to  be  much 
branched.  This  is  especially  noticeable  in  dried  specimens  (fig.  1, 
pi.  51).  The  secondary  "gills"  are  not  attached  to  the  primary  ones, 
however,  but  fit  in  between  and  beneath  them.  Branching  occurs  but 
rarely,  and  is  the  result  of  the  anastomosing  of  two  "gills"  in  the 
early  stages  of  development. 

2.  ORIGIN  AND  DEVELOPMENT  OF  THE  "GILLS" 

The  origin  and  development  of  the  lamellae  has  been  studied  in  a 
fairly  large  number  of  members  of  the  Agaricaceae.  In  all  of  these 
Atkinson  (1916)  recognized  two  general  types.  In  the  first,  which 
he  called  the  "Agaricus"  type,  the  hyphae  form  a  palisade  layer  at 
the  roof  of  a  well-developed  annular  cavity  which  appears  on  the 
under  side  of  the  pileus ;  and  from  this  palisade  layer,  which  is  the 
hymenium  primordium,  the  lamellae  grow  downward  into  the  cavity. 
In  the  second,  or  " Amanita"  type,  the  gills  originate  as  bars  radiat- 
ing out  from  the  stipe  to  the  under  surface  of  the  pileus.  The  origin 
and  development  of  the  "lamellae"  in  Schizophyllum  commune  is 
entirely  distinct  from  either  of  the  above  types.  The  gills  grow  out- 
ward from  a  palisade  layer  which  forms  the  lining  of  a  single  apical 
depression  or  cup. 

The  origin  of  a  "  gill ' '  is  evidenced  in  cross-sections  in  two  ways : 
either  a  split  appears  in  the  palisade  layer  and  the  edges  grow  out- 
ward (fig.  6,  pi.  56)  ;  or  a  small  area  of  the  palisade  layer  becomes 
loosened,  grows  outward  a  short  distance,  and  then  splits  in  the  middle 
to  a  point  beneath  the  original  primordial  layer  (fig.  9,  pi.  56).  In 
both  cases  the  growth  continues  in  the  same  manner.  The  hyphae 
beneath  the  edge  of  the  hymenium  on  each  side  of  the  split  grow  out- 
ward rapidly  and  cause  the  hymenial  edges  to  turn  downward,  and 
by  marginal  growth  a  pair  of  hymenial  plates  are  soon  formed  (figs. 
1—4,  pi.  57).  Growth  continues  at  the  edges  of  these  plates  through- 
out the  life  of  the  sporophore,  so  that  in  very  old  fruit  bodies  some 
gill  plates  may  be  comparatively  deep. 

Buller  (1909),  noting  the  fact  that,  in  cross-sections  of  the  mature 
specimens,  the  tramal  layer  was  split  to  different  depths,  thought  that 
the  "gills"  arose  entire  and  were  later  split  due  to  hygroscopic  ten- 
sions. This  theory  had  been  earlier  advanced  by  Fayod  (1889),  who 
claimed  that  specimens  grown  under  water  have  entire  "gills."  In 
attempting  to  demonstrate  Fayod 's  statement  it  was  found  that  sporo- 
phores  grow  with  difficulty  under  water  and  decay  after  a  few  days. 


462  University  of  California  Publications  in  Botany          LVoL-  7 

Those  "gills"  which  did  arise  under  these  conditions,  however,  showed 
no  departure  from  the  process  as  described  by  the  writer  above.  In 
all  cases  observed  the  plates  have  been  separated  at  the  edges  from 
the  very  first.  In  later  stages  they  may  be  separated  only  a  short  dis- 
tance toward  the  pileus,  or  they  may  be  split  to  any  depth  in  the 
tramal  hyphae  or  pileus,  or  even  completely  through  the  flesh  of  the 
pileus.  Each  "gill,"  after  it  unites  with  the  pileus  margin,  is  split 
more  deeply  at  the  outer  end,  and  the  depth  decreases  toward  the  stipe 
end,  as  does  likewise  the  size  of  the  "gill." 

The  splitting  or  loosening  of  the  hymenium  to  permit  the  origin 
of  the  paired  hymenial  plates  is  due  to  the  same  tensions  which  cause 
the  "gills"  themselves  later  to  be  split  to  different  depths.  The  addi- 
tion of  new  elements  to  the  hymenial  layer  does  not  keep  pace  with 
the  growth  of  the  hyphae  beneath  the  hymenium.  When  the  hyme- 
nium has  attained  a  certain  width  the  tension  upon  the  closely  crowded 
elements  of  the  hymenial  layer  is  so  great  that  it  is  either  split  longi- 
tudinally near  the  center  of  the  area,  or  the  palisade  elements  are 
loosened,  grow  outward  a  short  distance,  and  then  split.  Likewise 
the  gill  plates  are  split  apart  to  different  depths  due  to  the  tensions 
set  up  by  these  differences  in  the  rate  of  growth  at  different  regions 
of  the  sporophore.  The  most  rapidly  growing  region  is  at  the  margin 
of  the  pileus,  and,  while  growth  may  and  actually  does  take  place 
throughout  the  sporophore,  it  decreases  in  rapidity  from  the  periphery 
to  the  place  of  attachment  of  the  stipe.  Thus  the  gill  plates  are 
longer  at  the  periphery,  but  the  difference  between  the  rates  of  growth 
of  the  hymenium  and  subhymenial  and  tramal  layers  is  just  as  pro- 
nounced. As  a  result  the  hymenial  margins  are  incurved  more  at  the 
margin  of  the  pileus  and  the  gill  plates  are  gradually  drawn  apart. 

In  some  young  sporophores  the  two  hymenial  margins  are  separated 
by  a  considerable  layer  of  sterile  surface  which  is  level  with  the  hyme- 
nium (fig.  1,  pi.  60).  In  this  case  there  is  not  even  a  resemblance  to 
gills. 

From  the  evidence  at  hand  it  seems  that  the  so-called  "gills"  of 
Schizophyllum  commune  Fries  are  such  by  analogy  only,  being  act- 
ually two  adjacent  edges  of  hymenial  areas  which  arise  together,  but 
which  become  continuous  with  and  are  homologous  to  the  margin  of 
the  pileus.  They  increase  the  area  of  the  hymenium  as  do  gills,  and, 
when  in  a  moist  condition,  look  much  like  typical  gills ;  but  each  plate 
is  independent  of  the  other  from  the  first,  increasing  in  size  by  mar- 
ginal growth. 


1922]       Essig:  Morphology  of  Schizophyllum  commune  Fries        463 

3.  TAXONOMIC  INTERPRETATION  OF  THE  STRUCTURE  AND 
DEVELOPMENT  OF  THE  SPOROPHORES 

It  was  early  observed  that  while  Schizophyllum  was  presumed  to 
possess  gills,  the  structures  were  unique  among  the  members  of  the 
Agaricaceae.  Consequently  considerable  difficulty  has  been  experi- 
enced among  systematists  in  associating  this  genus  with  the  other 
members  of  the  family  from  which  it  is  so  distinct. 

Fayod  (1889)  believed  it  to  be  precisely  like  Panus,  except  that 
in  Panus  the  gills  were  entire.  He  classified  them  tinder  the  tribe 
Panoides,  and  noted  a  similarity  in  the  geographical  distribution  of 
the  two  genera.  Hennings  (1898),  following  Saccardo  (1887-1895), 
placed  Schizophyllum  in  the  tribe  Schizophylleae  with  Bhacophyllus, 
Oudcmansiella,  and  Pterophyllus,  but  stated  that  the  other  genera  do 
not  seem  to  belong  to  this  group.  Murrill  (1915)  put  it  in  the  tribe 
Agariceae  and  subtribe  Lepiotanae  along  with  Marasmius,  Lepiota,  and 
other  white-spored  members  of  the  Agaricaceae. 

All  these  writers  have  based  their  classification  upon  the  assump- 
tion that  the  hymenium  in  Schizophyllum  is  borne  upon  the  surface 
of  lamellae.  Since  this  is  not  the  case — for  the  hymenophore  while 
quite  complex  in  structure  bears  a  smooth  hymenium — the  fungus 
should  be  placed  in  the  family  Thellephoraceae.  In  this  family  it 
resembles  CypheUa  in  the  organization  of  the  sporophores,  for,  in  this 
genus,  according  to  De  Bary  (1887),  the  hymenium  lines  the  inner 
and  lower  surfaces  of  a  funnel-shaped  sporophore,  the  stipe  being 
attached  to  the  opposite  side  of  the  pileus  from  the  hymenium  (fig.  16, 
pi.  52).  The  early  stages  in  the  development  of  Schizophyllum  com- 
mune and  Stereum  hirsutum,  likewise,  have  much  in  common.  In  the 
later  stages,  however,  the  hymenium  of  Stereum  hirsutum  remains 
entire,  and  bears  no  resemblance  to  the  much  divided  hymenium 
of  Schizophyllum  commune.  Only  in  the  genus  Cladoderris  is  there 
anything  comparable  to  the  hymenial  plates  of  Schizophyllum.  Clado- 
derris is  somewhat  similar  to  Stereum,  but  differs  in  possessing  radiat- 
ing, branched  ribs  upon  the  hymenial  surface.  Some  species  of  Clado- 
derris have  the  pileus  margin  much  incised.  The  representatives  of 
the  genus  Cladoderris  are  chiefly  tropical,  and  are  known  to  the  writer 
only  through  descriptions  and  illustrations.  From  these  it  seems  that 
there  is  only  a  difference  in  degree  between  the  splitting  of  the  pileus 
margin  in  sporophores  of  Cladoderris  infundibuliformis  Fries  (cf. 
Hennings,  1898)  and  the  marginal  division  in  fruit  bodies  of  Schizo- 
phyllum commune. 


464  University  of  California  Publications  in  Botany          [VOL.  7 

V.  ECONOMIC  ASPECTS 
1.  GEOGRAPHICAL  DISTRIBUTION 

In  a  discussion  of  the  economic  importance  of  Schizophyllum  it 
seems  well  to  go  into  detail  concerning  its  distribution  throughout 
the  world,  as  any  consideration  of  the  amount  of  damage  done  must 
take  into  account  both  its  distribution  and  its  abundance  in  any  dis- 
trict. Fortunately  a  great  number  of  statements  have  been  published 
concerning  its  collection  in  various  places.  In  the  table  below  are 
given  by  continents  the  countries  or  regions  in  which  Schizophyllum 
has  been  collected  or  reported,  the  authority,  and  the  date  of  publi- 
cation of  the  article.  The  table  is  representative  rather  than  exhaus- 
tive, as  only  one  reference  to  a  locality  has  been  included. 

TABLE  OF  GEOGRAPHICAL  DISTRIBUTION 

Continent  Place  Authority  Date 

Eurasia  England  Cheesman,  W.  N.  1904 

Scotland  Paterson,  R.  H.  1877 

Sweden  Linnaeus,  C.  1753 

Germany  Hennings,  P.  1898 

France  Gueguen,  F.  1901 

Italy  Archangel!,  G.  1887 

Central  Asia  Sorokine,  N.  1890 

China  Roumeguere,  C.  1879 

Ceylon  Berkeley,  M.  J.,  and  Broome,  C.  E.      1871 

Africa  Tripoli  Baroni,  E.  1892 

Abyssinia  Saccardo,  P.  A.  1891 

Cape  of  Good  Hope         Berkeley,  M.  J.  1876 

Africa  Hennings,  P.  1891 

North  America  Canada  Dearness,  J.  1896 

Eastern  United  States      Atkinson,  G.  F.  1901 

Middle  Western  U.  S.      Heald,  F.  D.  1906 

Oregon  Griffin,  F.  L.  1911 

California  Smith,  R.  E.,  and  E.  H.  1911 

Mexico  Patouillard,  N.  1887 

West  Indies  Massee,  G.  1892 

South  America  Brazil  Averna-Sacca,  R.  1916 

Australia  Australia  MacAlpine,  D.  1902 

New  Zealand  Buchanan,  J.  1874 

The  sporophores  of  the  Schizophyllum  in  the  £eld  are  usually  small 
and  inconspicuous.  When  found  they  are  usually  in  large  numbers 
within  a  small  area  on  a  log  or  tree.  Only  an  occasional  tree  or  log 
displays  them  in  this  region  (California).  Heald  (1906)  reported 
that  every  tree  of  a  small  orchard  of  cherries  in  Nebraska  was  infected 
with  the  fungus,  but  this  seems  to  be  an  extreme  case. 


1922]       Essig:  Morphology  of  Schizophyllum  commune  Fries        465 


2.  LIST  OF  HOST  PLANTS 

A  large  number  of  plants  have  been  mentioned  in  scientific  liter- 
ature as  hosts  of  the  sporophores  of  Schizophyllum.  It  is  not  clear  in 
most  of  these  references  whether  the  specimens  were  found  upon  living 
or  dead  plants.  The  distinction  is  of  some  importance  in  the  consid- 
eration of  the  economic  aspects  of  the  fungus.  The-  information  in  the 
following  table  has  been  obtained  from  publications,  from  the  spoken 
word  of  collectors  whom  the  writer  has  been  fortunate  enough  to  meet, 
from  specimens  in  the  Herbarium  of  the  University  of  California,  and 
from  observations  in  the  field.  Dates  are  given  for  references  to 
publications  only. 


TABLE  OF  HOST  PLANTS 


Family 

Pinaceae 


Gramineae 

Palmaceae 
Juglandaceae 

Betulaceae 
Fagaceae 


Moraceae 
Lauraceae 

Rutaceae 

Tiliaceae 

Aceraceae 

Hippocastanaceae 

Rosaeeae 


Leguminosae 


Rubiaceae 


Name 

Yellow  Pine 

(Pinus  ponderosa) 
Western  Hemlock 

(Tsuga  heterophylla) 
Sugar  Cane 

(Saccharum  officinarum) 
Bamboo  (Bambusa  sp.) 
Royal  Palm  (Oreodoxa  regia) 
English  Walnut  (Juglanssp.) 
Hickory  (Hicoria  sp.) 
Alder  (Alnus  sp.) 
Birch  (Betula  sp.) 
Beech  (Fagus  sp.) 
Oak  (Quercus  serrata) 
Chestnut  (Costarica  sp.) 
Mulberry  (Morus  sp.) 
California  Baytree 

(Umbellularia  calif  arnica) 
Oranges  and  Lemons 

(Citrus  sp.) 
Linden  (Tilia  sp.) 
Maple  (Acer  sp.) 
Horse  Chestnut 

(Aesculus  Hippocastanum) 
Apple  (Pynis  malus) 
Pear  (Pyrus  communis) 
Cherry  (Prunus  cerasus) 
Peach  (Primus  persica) 
Almond  (Prunus  communis) 
Pterocarpus  indicus 
Acacia  (Acacia  sp.) 
Hardy  Catalpa 

(Catalpa  speciosa) 
Coffee  (Coffea  sp.) 


Authority 
Stillinger,  C.  R. 

Stillinger,  C.  R. 
Ray,  J. 

Home,  W.  T. 
Home,  W.  T. 
Smith,  R.  E.,  and  E.  H. 
Dearness,  J. 
Linnaeus,  C. 
Adams,  J.  F. 
Rumbold,  C. 
Roumeguere.  C. 
Stevens,  F.  L. 
Prillieux  and  Delacroix 
Brown,  V.  S. 

Smith,  R.  E.,  and  E.  H. 

Hennings,  P. 
Hasselbring,  H. 
Gueguen,  F. 

Fulton,  H.  R. 
Baroni,  E. 
Griffin,  F.  L. 
Camp,  A.  F. 
Kellogg,  E.  S. 
Kew  Bull.  Misc.  Inf. 
Seen  in  the  field 
Stevens,  N.  E. 

Averna-Sacca,  R. 


Date 


1896 


1911 
1896 
1783 
1918 
1910 
1879 
1913 
1893 


1911 

1898 
1907 
1901 

1912 
1892 
1911 


1910 
1912 
1916 


466  Uiviversity  of  California  Publications  in  Botany          [VoL-  7 


3.  EXTREME  HARDINESS  OF  THE  FUNGUS 

Schizophyllum  is  able  to  persist  under  very  adverse  circumstances. 
Its  unusual  vitality  is  displayed  in  three  ways:  (1)  the  sporophores 
are  able  to  endure  long  periods  of  drought;  (2)  the  mycelium  can 
grow  upon  almost  any  moist  organic  substance;  and  (3)  the  sporo- 
phores possess  the  ability  to  regenerate  lost  parts. 

Buller  in  1909  called  attention  to  the  long  period  over  which  the 
sporophores  can  retain  their  vitality.  He  stated  that  "whilst  in  the 
dried  condition  a  fruit  body  can  retain  its  vitality  for  at  least  two 
years,  and,  with  intermittent  revivals,  for  at  least  three  years. ' '  Later 
(1912)  he  and  Cameron  found  that  the  fruit  bodies  could  endure 
sudden  changes  of  temperature,  suspension  in  a  vacuum,  extreme  cold, 
or  a  long  period  in  darkness.  In  this  respect  they  resemble  certain 
seeds  and  mold  spores. 

A  mycelium  produced  either  from  spores  or  pieces  of  sporophores 
will  grow  upon  a  whole  series  of  substances.  Some  of  the  materials 
upon  which  the  hyphae  grow  well  are  such  starchy  media  as  potato 
tubers,  corn  meal,  rice,  "Cream  of  "Wheat,"  and  lima  beans;  sugary 
media  such  as  beets,  prune  juice,  and  grapes ;  upon  agar  and  gelatin 
nutritive  media;  and  upon  dung,  a  wood  decoction,  or  dead  leaves. 
Kellogg  (1915)  grew  the  fungus  from  spore  to  spore,  or  through  all 
of  its  life  history,  upon  sterilized  potato  plugs  in  glass  flasks,  showing 
that  Schizophyllum  can  exist  in  an  entirely  saprophytic  condition. 
Earlier  Rumbold  (1910)  had  produced  sporophores  on  bread  from 
spore  cultures,  but,  although  these  bore  basidia  on  a  definite  hymenium, 
no  spores  developed. 

Experiments  have  been  carried  on  to  determine  to  what  extent  the 
sporophores  can  regenerate  lost  parts.  The  fruit  bodies  studied  were 
grown  upon  blocks  of  Acacia  wood  kept  in  moist  chambers  in  the 
laboratory.  In  one  case  about  one-half  of  the  pileus  at,  the  distal  ends 
of  mature  sporophores  was  removed  by  cutting  with  a  sharp  knife. 
Some  of  the  specimens  were  left  in  the  original  position,  and  others 
were  inverted  by  reversing  the  position  of  the  blocks  of  wood  upon 
which  they  were  growing.  Where  the  mutilated  sporophores  were 
left  in  position  growth  ceased  at  the  cut  edge,  but  continued  in  a 
normal  manner,  though  rather  slowly,  at  the  pileus  margins  to  the 
side.  Most  of  the  inverted  specimens  ceased  growth  altogether.  In 
one  case,  however,  in  a  few  days  the  margin  at  one  side  began  to  turn 
and  grow  outward  in  a  horizontal  direction  with  the  hymenium  facing 


1922]       Essi-g:  Morphology  of  Schizophyllum  commune  Fries        467 

downward.  At  the  end  of  17  days  a  normal  sporophore  about  1  cm. 
in  diameter  had  developed  (fig.  2,  pi.  60). 

In  another  experiment  the  entire  hymenophore  was  removed  by 
cutting  across  the  stipe  at  the  distal  end.  Specimens  left  in  the  orig- 
inal position  produced  new  hymenophores  in  one  of  two  methods.  If 
the  stipe  was  small  at  the  cut  end,  only  one  new  sporophore,  as  a  rule, 
developed  by  the  growth  of  hyphae  out  through  the  cut  end  of  the 
stipe  (fig.  3,  pi.  60).  This  developed  in  the  usual  way.  If  the  cut 
end  of  the  stipe  was  of  considerable  area,  several  small  sporophores 
developed.  These  grew  in  the  usual  way  except  that  the  hymenial 
plates  arose  in  position  with  respect  to  the  old  stipe  and  not  as  though 
the  separate  sporophores  were  distinct  individuals  (fig.  I8d,  pi.  52). 
The  sporophores  more  advantageously  placed,  that  is,  at  the  upper 
edge  of  the  stipe,  grew  more  rapidly  and  became  much  larger  than 
those  at  the  sides.  The  sporophores  might  be  cut  away  to  within  a 
millimeter  of  the  base  of  the  stipe  and  still  a  new  sporophore  would 
develop  upon  the  cut  end.  The  specimens  used  were  mature  and  were 
shedding  spores,  but  were  comparatively  young.  Thus  the  sporo- 
phores have,  at  least  while  still  young  and  fresh,  the  ability  to  regen- 
erate practically  the  entire  body. 

Stipes  with  the  entire  hymenophore  removed  and  in  an  inverted 
position  in  all  cases  produced  either  one  or  several  small  sporophores 
upon  the  cut  end,  but  growth  soon  ceased.  Sections  through  these 
specimens  showed  that  they  had  stopped  growing  either  in  the 
"peziza"  stage  or  after  one  or  two  hymenial  plates  had  been  formed 
(figs.  19-20,  pi.  52).  The  inability  of  the  sporophores  to  develop 
further  in  an  inverted  position  is  doubtless  due  to  their  lack  of  power 
to  change  the  polarity  of  the  different  parts  with  respect  to  the 
reaction  to  the  force  of  gravity.  That  gravity  is  the  form-stimulus 
was  clearly  demonstrated  by  Hasselbring  (1907). 

4.  KELATION  OF  THE  MYCELIUM  TO  CELLS  OF  DEAD  WOOD 

Upon  sectioning  dead  wood  it  is  found  that  there  is  an  unexpected 
paucity  of  mycelium  in  the  tissues  infected  by  Schizophyllum.  Wood 
brought  in  from  the  field  in  a  dry  condition  covered  with  the  sporo- 
phores may  be  sectioned  and  fail  to  display  any  mycelium  in  a  large 
percentage  of  the  sections.  In  some,  however,  a  few  hyphae  can  be 
seen. 

The  hyphae  of  this  fungus  are  shown  by  sections  to  be  confined 
almost  entirely  to  the  tracheae  of  the  wood  (pi.  61).  In  some  ducts 


468  University  of  California,  Publications  in  Botany          [VoL-  7 

there  may  be  only  one  or  two,  but  in  others  the  lumen  may  be  almost 
filled.  In  all  cases  the  mycelium  varies  considerably  in  size,  the  walls 
are  thin,  and  branching  is  infrequent.  The  lateral  tubercles  are 
present  upon  the  walls  of  some  of  the  hyphae. 

Wherever  the  mycelium  is  found  in  wood  in  earlier  stages  of  decay 
there  is  present  a  series  of  small,  globular  masses  of  a  brown  exudate. 
The  mycelium  of  Schizophyllum  growing  upon  artificial  media  pro- 
duces a  like  substance,  so  that  found  in  the  wood  is  probably  pro- 
duced by  the  hyphae.  In  certain  regions  the  droplets  are  so  numerous 
that  the  wood  is  discolored.  They  account  for  the  black  or  dark  brown 
layers  often  seen  near  the  edge  of  the  decayed  areas.  In  regions  of 
advanced  decay  they  have  entirely  disappeared. 

Cross-sections  through  the  limb  of  a  living  tree  which  was  infested 
with  the  fungus  in  a  narrow  area  along  one  side  of  the  limb  showed 
that  the  infected  area  extended  in  a  radial  direction  to  the  center  of 
the  limb.  Some  pieces  of  this  limb  were  placed  in  moist  chambers. 
In  a  few  days  tufts  of  hyphae  grew  out  of  the  wood  at  the  edges  of 
the  infected  area  near  the  living  wood  and  only  a  few  scattering  threads 
could  be  seen  in  the  central  part  of  the  discolored  tissues.  Thin  sec- 
tions also  disclose  the  fact  that  the  greater  part  of  the  vegetative 
mycelium  is  near  the  living  wood  in  partially  killed  limbs  or  trunks 
of  trees. 

The  decay  is  marked  at  first  by  a  darkening  of  the  tissues.  There 
are  dark  brown  or  black  layers  near  the  edge  of  the  darkened  areas. 
At  later  stages  delignification  sets  in,  and  the  decayed  areas  become 
straw-colored.  The  cell  walls  become  softened,  but  retain  their  struc- 
ture for  a  long  period.  The  mycelium  of  Schizophyllum  is 'frequently 
found  in  areas  of  advanced  decay  along  with  the  hyphae  of  other 
fungi,  and  it  is  difficult  to  determine  how  much  of  the  decay  is  due  to 
the  work  of  Schizophyllum  commune  alone. 


5.  GBOWTH  UPON  FRESH  WOOD  AND  LIVING  TISSUES 

Freshly  cut  pieces  of  Acacia  wood  were  placed  in  moist  chambers 
and  spores  of  Schizophyllum  were  planted  upon  different  tissues. 
Acacia  wood  was  chosen  because  sporophores  are  found  in  abundance 
upon  the  dead  wood  of  this  tree.  The  pieces  of  wood  were  kept  moist 
enough  to  cause  the  spores  to  germinate.  The  experiment  was  carried 
on  for  two  months.  At  the  end  of  that  time  it  was  found  that  the 


1922]       Essig:  Morphology  of  Schizophyllum  commune  Fries         469 

hyphae  had  not  penetrated  through  the  fresh,  uninjured  bark,  or  cor- 
tical tissues,  or  through  the  wood  tissues  in  a  lateral  direction,  but  had 
grown  through  the  wood  in  the  direction  of  the  tracheae. 

Attempts  to  prove  the  parasitism  of  this  organism  were  made  by 
Gueguen  (1901)  and  Fulton  (1912)  with  negative  results.  Rumbold 
(1910)  stated  that  Tuzson  (1905),  (whose  paper  is  not  available)  grew 
the  fungus  upon  fresh  (frais)  beech  wood.  Kellogg  (1915)  was  not 
able  to  demonstrate  the  mycelium  of  Schizophyllum  in  the  inoculations 
made  upon  fruit  trees. 

In  my  inoculation  experiments  young  fruit  trees  of  apple,  pear, 
and  plum  were  used.  Inoculations  were  made  from  agar  plates  of 
pure  cultures  of  the  mycelium.  The  limbs  of  these  trees  were  either 
split  through  the  center  or  cut  into  from  the  surface  to  varying  depths. 
A  sterile  knife  was  used  in  the  incisions.  The  mycelium  with  sub- 
stratum was  transferred  to  the  cut  or  slit  surface  and  the  wound  was 
tied  up  with  string  and  covered  with  waxed  paper,  a  layer  of  wet 
absorbent  cotton,  and  another  layer  of  waxed  paper.  The  purpose  of 
the  wet  cotton  and  waxed  paper  was  to  prevent  the  drying  out  of  the 
exposed  surfaces.  At  intervals  of  one  week  after  the  time  of  inocu- 
lation certain  limbs  were  removed,  examined,  and  sections  made  to 
determine  if  there  had  been  any  growth  of  the  mycelium  into  the 
living  tissues.  In  most  cases  no  trace  of  the  mycelium  could  be  found 
in  the  wood.  In  two  or  three  branches  there  was  a  darkening  of  the 
surface  exposed  to  the  mycelium,  and  in  the  vessels  the  typical  exudate 
which  is  produced  by  the  mycelium,  but  so  little  mycelium  was  found 
in  the  ducts  that  the  growth  could  not  be  identified,  with  certainty, 
as  Schizophyllum.  In  only  one  branch  was  there  an  unmistakable 
infection.  This  was  in  a  limb  of  a  plum  tree  cut  off  three  months 
after  inoculation.  The  mycelium  had  penetrated  to  a  maximum  depth 
of  3  mm.  and  the  infected  area  was  about  4  cm.  long  and  1  cm.  in 
width.  Many  hyphae  were  present  in  the  vessels,  and  a  few  could  be 
seen  in  the  medullary  ray  cells.  There  was  the  characteristic  darkened 
layer  at  the  edge  of  the  infection  about  0.5  mm.  thick.  From  the 
results  of  previous  investigations  and  these  experiments  it  is  evident 
that  the  living  woody  tissues  can  be  penetrated  and  killed  by  the 
mycelium  of  Schizophyllum,  but  that  this  process  takes  place  slowly 
and  with  difficulty. 


470  University  of  California  Publications  in  Botany          [VOL.  7 


6.  METHODS  OF  INFECTION  UNDER  NATURAL  CONDITIONS 

There  have  been  many  expressions  of  opinion  in  published  papers 
concerning  the  manner  in  which  living  trees  become  infected  with  the 
mycelium  of  Schizophyllum.  Infection  takes  place  in  three  more  or 
less  distinct  ways:  (1)  by  entering  through  surfaces  exposed  by 
mechanical  injury,  (2)  by  attacking  parts  of  trees  weakened  through 
certain  physiological  causes,  and  (3)  by  gaining  admission  through 
tissues  first  injured  or  killed  by  other  organisms. 

As  regards  mechanical  injury,  in  Stevens  and  Hall  (1910)  it  is 
stated  that  "apparently  this  disease  starts  in  roots  injured  by  tools 
during  cultivation. ' '  Professor  Home  of  the  University  of  California 
has  observed  an  infection  beneath  an  apple  tree  graft  (fig.  1,  pi.  58) 
that  had  not  been  properly  sealed  with  wax.  An  infection  at  a  crotch 
split  in  a  peach  tree  (fig.  2,  pi.  58)  was  reported  by  A.  P.  Camp,  a 
student  in  the  University  of  California.  Any  woody  part  exposed 
by  injury  forms  a  possible  place  of  entrance  for  the  fungus. 

Weakening  of  the  trees  by  excess  water,  or  lack  of  proper  drain- 
age, was  decided  by  Guegen  (1901)  to  be  a  contributory  cause  of 
infection  in  horse  chestnut  trees.  Stone  (1910)  found  that  sun  scald 
and  scorch  of  maple  trees  was  followed  by  Schizophyllum  and  other 
fungi.  The  writer  has  seen  the  sunburned  parts  of  California  Bay 
trees  covered  with  sporophores.  It  is  evident  that  trees  weakened  by 
certain  physiological  agents  fall  prey  to  this  fungus,  and  probably 
any  loss  of  vitality  on  the  part  of  the  tree  makes  it  susceptible  to  the 
attacks  of  Schizophyllum. 

Wilson  (1912)  found  that  the  sporophores  issued  through  the 
burrows  made  by  the  shot  hole  borer  (Xyleborus  dispar  Fabricus). 
Griffin  (1911)  stated  that  cherry  trees  weakened  by  bacterial  gum- 
mosis  are  frequently  attacked  and  killed  by  Schizophyllum  commune. 

No  evidence  has  been  brought  forward  in  available  literature  to 
show  that  Schizophyllum  is  able  to  infect  healthy  trees,  or  those  not 
injured  or  weakened  in  some  way.  It  seems  likely  that  infection  can 
be  prevented  by  using  care  in  cultivation,  by  painting  wounds  made 
in  pruning,  by  preventing  crotch  splitting,  by  protecting  the  trees  from 
sunburning,  and  by  keeping  them  free  from  other  diseases. 


1922]       Essig:  Morphology  of  Schizophyllum  commune  Fries        471 

7.  ASSOCIATION  WITH  OTHER  WOOD  DECAY  FUNGI 

Fulton  (1912)  found  that  in  an  apple  collar  rot  which  he  described 
Schizophyllum  commune  was  present  along  with  two  other  organisms. 

Stone  (1910)  found  in  sun  scald  and  scorch  of  maples  that  it  was 
followed  first  by  a  canker  fungus  (Nectria  cinnabarina) ,  and  then  by 
Schizophyllum  and  Polystictus. 

In  the  ease  of  the  apple  graft  mentioned  above,  the  writer  took 
the  branch,  sawed  it  into  sections,  and  placed  some  of  the  sections  in 
a  moist  chamber.  From  the  decayed  area  a  mass  of  mycelium  appeared 
which  was  not  of  Schizophyllum,  but  as  it  has  not  yet  produced  any 
fruit  bodies  it  cannot  be  identified. 

Observations  show  that  the  fruit  bodies  of  Schizophyllum  are  pro- 
duced in  a  comparatively  short  time  after  inoculation  has  taken  place. 
I  have  noted  several  times  in  the  field  that  this  fungus  is  the  first  to 
appear  upon  uprooted  trees.  Later,  sporophores  of  Polystictus, 
Polyporus,  Tremella,  Hydnum,  and  other  fungi  are  produced.  Most 
of  the  pieces  of  wood  I  have  collected  in  the  field,  which  have  only 
sporophores  of  Schizophyllum  upon  them,  when  placed  in  moist  cham- 
bers long  enough  will  produce  sporophores  of  Hydnum  or  Polystictus, 
or  both,  long  after  a  great  number  of  fresh  Schizophyllum  fruit  bodies 
have  been  formed.  Since  the  hyphae  of  these  other  fungi  were  in 
the  wood  along  with  that  of  Schizophyllum,  it  is  apparent  that  the 
latter  fungus  develops  sporophores  in  a  much  shorter  time  than  the 
others  present.  Schizophyllum,  forming  fruit  bodies  first  upon  a  dis- 
eased tree,  is  naturally  accused  of  being  the  parasite  causing  the  dam- 
age. The  writer  believes  that  much  or  even  most  of  the  injury  to  trees 
attributed  to  this  fungus  is  actually  caused  by  the  fungi  so  often 
associated  with  it,  such  as  Polystictus  versicolor,  which  is  beyond  doubt 
a  parasite.2 


2  Proof  of  the  parasitism  of  P.  versicolor  was  given  by  W.  W.  Thomas  in  1916 
at  the  University  of  California  in  a  thesis  submitted  for  a  Master's  degree. 
Mr.  Thomas  inoculated  living  trees  with  positive  results  as  regards  infection. 


472  University  of  California  Publications  in  Botany          [VOL.  7 


VI.  SUMMARY  AND  CONCLUSION 

In  summarizing  the  morphology  and  development  of  Schizophyllum 
it  may  be  said  that : 

1.  The  sporophores  vary  greatly  as  to  form  and  shape. 

2.  The  segments  of  the  mycelium  and  sporophores  and  spores  are 
regularly  binucleate. 

3.  The  fungus  develops  its  sporophores  as  does  no  other  member 
of  the  Hymenomycetes  so  far  studied,  the  hymenium  primordium  aris- 
ing in  an  apical  cavity. 

4.  The  "gills"  arise  upon  the  surface  of  an  apical  depression  due 
to  tensions  set  up  by  unequal  rates  of  growth. 

5.  The  "lamellae"  are  such  by  analogy  only,  being  the  edges  of 
smooth  hymenial  areas,  and  therefore  Schizophyllum  belongs  in  the 
family  Thellephoraceae. 

As  regards  the  economic  aspects  of  Schizophyllum,  it  has  been 
shown  that : 

1.  Members  of  this  genus  are  found  throughout  the  tropical  and 
temperate  zones  of  the  world. 

2.  They  live  upon  a  great  number  of  woody  plants,  both  in  the 
Dicotyledonae,  Monocotyledonae,  and  Gymnospermae. 

3.  The  fungus  possesses  unusual  vitality. 

4.  The  mycelium  is  found  only  in  small  amount  in  infected  wood. 

5.  It  can  grow  upon  fresh  wood,  and,  under  very  favorable  condi- 
tions, living  wood. 

6.  Natural  infection  takes  place  through  some  injured  or  weakened 
part  of  the  tree. 

7.  The  fungus  is  usually  associated  with  other  parasitic  fungi, 
which  probably  do  most  of  the  damage  attributed  to  Schizophyllum, 
but  escape  attention  due  to  the  longer  time  necessary  for  them  to 
produce  fruit  bodies. 


1922]       Essig:  Morphology  of  Schizophyllum  commune  Fries        473 


VII.  ACKNOWLEDGMENTS 

For  helpful  advice  and  criticism  in  the  preparation  of  this  paper 
the  writer  wishes  to  thank  and  give  credit  to  Dr.  W.  A.  Setchell,  Dr. 
T.  H.  Goodspeed,  and  Professor  W.  T.  Home.  Mr.  C.  E.  Stillinger 
of  the  Bureau  of  Plant  Industry,  United  States  Department  of  Agri- 
culture, has  given  valuable  information  concerning  certain  phases  of 
the  work.  In  the  collection  of  specimens  aid  has  been  given  by  Mr. 
A.  F.  Camp  and  others. 


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1900.     Sur    la    cytologie    des    Hymenomycetes.      Comptes    Rendus,    Soc.    de 

Biologic,  Paris,  vol.  131,  p.  121. 
MASSEE,  G. 

1892.  Some  West  Indian  fungi.     Journal  of  Botany,  vol.  30,  pp.  161-164, 

pi.  321-323. 
MORGAN,  A.  P. 

1890.     Mycological  observations.     LI.     Botanical  Gazette,  vol.  15,  pp.  84-86. 

MURRILL,   W.   A. 

1915.     Agaricaceae.     North  American  Flora,  vol.  9,  no.  4,  pp.  237,  238. 
PATERSON,  E.  H. 

1877.     Exotic  fungi  of  Scotland.     Grevillea,  vol.  5,  p.  112. 
PATOUILLARD,  N. 

1887.     Note  sur  quelques  champignons  de  1'herbier  du   Museum   d'histoire 

naturelle  de  Paris.     Journal  de  Botanique,  vol.  1,  pp.  169-171. 
PRILLIEUX,  E.,  &  DELACROIX,  G. 

1893.  Diseases  of  the  Mulberry.     Bulletin  du  Ministre  de  1'Agricole,  vol.  12, 

no.  5,  pp.  452-472. 
PRITZEL,  G.  A. 

1851.     Thesaurus  literaturae  botanicae  omnium  gentium  inde  a  rerum  botani- 
carum  initiis  ad  nostra  usque  tempera,  quindecim  millia  operum 
recensens.     Leipzig. 
BAY,  J. 

1896.     On  the  diseases  of  the  sugar  cane.     Bulletin  de  la  Societe  Mycologique 
de  France,  pp.  139-143. 

EOSENVINGE,  K. 

1886.     Sur  les  noyaux  des  Hymenomycetes.    Annales  des  Sciences  Naturelles, 
s6r.  7,  Botanique,  vol.  3,  pp.  75—93,  pi.  1. 

EOUMEOUERE,  C. 

1879.     Chronique   mycologique.     Revue   Mycologique,    vol.    1,   pp.    145,    146, 
150-154,  pis.  2-4. 

RUMBOLD,  C. 

1910.     Les  champignons  destructeurs  du  bois.     Annales  de  la  Science  Agro- 
nomique,  ser.  3,  vol.  5,  no.  6,  pp.  402—404,  fig.  25. 


476  University  of  California  Publications  in  Botany          [VOL-  7 

SACCARDO,  P.  A. 

1887.     Sylloge  fungorum  omnium  hucusque  cognitorum,  vol.  5,  pp.  654-656. 
1891.     Ibid.,  vol.  9,  p.  81. 
1895.     Ibid.,  vol.  11,  p.  42. 
1899.     Ibid.,  vol.  14,  p.  123. 
1911.     Ibid.,  vol.  20,  pp.  750,  751. 

SCHROETER,  J. 

1889.     Die  Pilze  Schlesiens,  vol.  3,  fasc.  553. 

SMITH,  B.  E.  &  E.  H. 

1911.  California  plant  diseases.     California  Agricultural  Experiment   Sta- 

tion, Bulletin  no.  218,  pp.  1088,  1089,  1140,  1173,  figs.  16,  65. 
SMITH,  W.  G. 

1884.     Fungus  on  ensilage.     Garden  Chronicle  II,  vol.  22,  p.  405. 

SOROKINE,   N. 

1889-1890.     Cryptogamique  flora  de  central  Asia.     Revue  Mycologique,  vols. 

11,  12. 
STEVENS,  F.  L. 

1913.     The  fungi  which  cause  plant  disease.     New  York. 
STEVENS,  F.  L.,  &  HALL. 

1910.     Diseases  of  economic  plants.     New  York. 
STEVENS,  N.  E. 

1912.  Wood  rots  of  the  hardy  catalpa.     Phytopathology,  vol.  2,  no.  3,  pp. 

114-119. 
STONE,  G.  E. 

1910.     Shade  tree  troubles.     Beport  of  the  Massachusetts  Agricultural  Ex- 
periment Station,  pt.  2,  pp.  52-55. 
TUZSON,  J. 

1905.     Anatomische  und  mykologische  Untersuchungen  uber  die  Zersetzung 

und  Konservierung  des  Botbuchenholzes.     Berlin. 
WAGER,  H. 

1893.     On  the  nuclear  divisions  in  the  Hymenomycetes.     Annals  of  Botany, 

vol.  7,  pp.  489-514,  pi.  24-26. 
WILSON,  H.  F. 

1913.  The  shot  hole  borer  of  the  Northwest;  or  the  pear  blight  beetle  of 

the  East.    Biennial  Crop  Pest  and  Horticultural  Beport,  1911-1912, 
Oregon  Agricultural  College  Experiment  Station,  pp.  97-107,  fig.  1. 
WINTER,  H.  G. 

1884.     Die  Pilze  Deutschlands,  Oesterreichs  und  der  Schweiz.     Babenhorst, 
L.,  Kryptogamen-Flora,  vol.  1,  p.  493. 

(AUTHOR  UNKNOWN.) 

1910.     A  disease   of  Pterocarpus   indicus.     Royal   Botanical    Garden,   Kew. 
Bulletin  of  Miscellaneous  Information,  no.  3,  pp.  95,  96. 


EXPLANATION  OP  PLATES 
PLATE  51 

Fig.  1.  Group  of  sporophores  in  a  dry  condition,  viewed  from  the  lower 
side.  2  diameters. 

Fig.  2.  Group  of  sporophores  in  a  moist  condition,  as  seen  from  below. 
Some  of  the  smaller  specimens  at  the  base  of  the  group  have  been  cut  away. 
1%  diameters. 


[478] 


UNIV.    CALIF.    PUBL.    EOT,    VOL.    7 


[  ESSIG  ]    PLATE    51 


PLATE  52 

Fig.  1.  Form  of  sporophores  growing  upon  an  under  surface,  a,  side  view 
of  fruit  bodies  in  position,  b,  the  hymenium  of  a  typical  fruit  body  viewed 
from  below,  showing  the  gill  plates  radiating  outward  from  a  region  near  the 
center  of  the  hymenium.  y2  natural  size. 

Fig.  2.  Form  of  fruit  bodies  growing  upon  a  vertical  surface,  a,  three 
sporophores  in  position,  b,  arrangement  of  the  lamellar  plates  in  a  sporophore 
grown  upon  a  vertical  substratum.  y2  natural  size. 

Fig.  3.  Form  of  fruit  bodies  growing  on  an  upper  surface,  a,  position 
assumed  by  sporophores  upon  the  upper  surface  of  a  limb,  b,  typical  arrange- 
ment of  the  lamellar  plates.  %  natural  size. 

Figs.  4-15.  Views  of  young  actively  growing  fruit  bodies  from  the  under 
side  to  show  the  origin  and  placement  of  the  lamellar  plates  or  ridges.  All  5 
diameters.  Fig.  4,  a  sporophore  with  a  smooth  hymenium  primordium  just  prior 
to  the  formation  of  lamellar  ridges.  Fig.  5,  a  fruit  body  with  a  single  lamellar 
ridge.  Fig.  6,  a  single  lamellar  ridge  with  the  sides  so  far  separated  by  sterile 
hyphae  as  to  become  merely  edges  of  the  hymenium  primordium.  Fig.  7,  a 
specimen  with  four  newly  formed  lamellar  ridges.  Figs.  8-14,  six  sporophores 
with  some  isolated  ridges  and  some  extending  to  the  edge  of  the  pileus.  Fig.  15, 
a  lateral  sporophore  with  the  lamellar  ridges  widening  into  sterile  areas  towards 
the  base. 

Fig.  16.  Sporophore  of  Cypliella  Urbani.  3  diameters.  (After  Engler  and 
Prantl.) 

Figs.  17-18.  Regeneration  in  position,  a,  a  small  sporophore  showing  with 
a  broken  line  where  the  hymenophore  was  removed,  b,  face  view  of  the  hymeno- 
phore  removed.  18c,  side  view  of  the  sporophore  after  seven  days,  d,  face  view 
of  the  same,  showing  five  small  sporophores  formed  upon  the  cut  end  of  the  old 
stipe.  All  1%  diameters. 

Fig.  19.  Regeneration  inverted,  c,  a  small  fruit  body  showing  where  the 
end  was  cut  away,  d,  a  median  section  of  the  same  thirty  days  later.  Only  one 
pair  of  lamellar  plates  was  formed.  1%  diameters. 

Fig.  20.  Regeneration  inverted,  c,  a  small  sporophore  showing  where  the 
end  was  removed,  d,  the  same  a  week  after  the  apex  had  been  cut  away,  show- 
ing three  very  small  sporophores  formed  upon  the  cut  end  of  the  inverted  stipe. 
These  developed  no  further.  1%  diameters. 

Fig.  21.  A  transverse  section  through  a  sporophore  when  in  a  dry  state, 
showing  the  revolute  lamellar  plates,  and  their  arrangement.  5  diameters. 

Fig.  22.  A  transverse  section  through  the  same  sporophore  represented  in 
fig.  21,  but  drawn  while  the  sporophore  was  in  a  moist  condition.  5  diameters. 


[480] 


UNIV.    CALIF.    PUBL.    BOT.   VOL.    7 


[ ESSIG  ]    PLATE    52 


V 


19 


20 


22 


PLATE  53 

A  sporophore  in  a  semi-moist  condition,  as  seen  from  below.  The  hymenium 
is  shown  to  be  divided  into  four  areas,  three  of  which  are  much  smaller  than 
the  fourth.  Several  newly  formed  isolated  pairs  of  lamellar  plates  can  be  seen, 
as  well  as  three  very  small  ridges  near  the  center  of  the  hymenophore  which 
arose  in  an  early  development  stage  but  remained  isolated.  10  diameters. 


[482] 


UNIV.   CALIF.    PUBL.    BOT.   VOL.   7 


[  ESSIG  ]    PLATE    53 


PLATE  54 

Fig.  1.  Part  of  a  typical  vegetative  hypha  to  show  the  structural  charac- 
ters. Clamp  connections  are  shown  at  each  septum.  The  nuclei  are  near  the 
center  of  each  cell.  1500  diameters. 

Fig.  2.  Portion  of  a  vegetative  hypha  covered  with  lateral  projections. 
1500  diameters. 

Fig.  3.  Hyphae  which  form  the  hairy  covering  of  the  pileus.  They  are 
usually  unicellular,  the  nuclei  being  near  the  base  of  the  cell.  In  this  drawing 
a  portion  of  each  cell  1.4  mm.  long  was  left  out.  This  would  represent  a  distance 
of  about  210  cm.  on  the  drawing  paper.  1500  diameters. 

Fig.  4.  Portion  of  a  longitudinal  section  through  the  flesh  of  a  very  young 
sporophore  to  show  the  hyphal  structure.  1500  diameters. 

Fig.  5.  Same  as  in  fig.  4,  except  that  the  section  was  taken  from  an  old 
sporophore.  1500  diameters. 

Fig.  6.  Portion  of  the  hymenium,  showing  one  mature  and  one  immature 
basidium.  1500  diameters. 

Fig.  7.  Six  typical  spores,  stained  in  safranin  and  gentian  violet  to  show 
the  nuclei.  2500  diameters. 

Fig.  8.  Germinating  spores  in  various  stages  of  development  after  being 
in  distilled  water  for  48  hours.  Stained  in  safranin.  1500  diameters. 


[484] 


UNIV.    CALIF.    PUBL.    BOT.    VOL.    7 


[  ESSIG  ]    PLATE    54 


PLATE  55 

Fig.  1.  Longitudinal  median  section  through  a  young  fruit  body  which  is 
practically  undifferentiated.  There  is  a  region  near  the  apex  which  stains 
more  deeply  and  is  the  seat  of  later  developments.  25  diameters. 

Fig.  2.  Similar  to  fig.  1,  but  a  later  stage,  showing  the  first  appearance 
of  the  apical  cavity.  25  diameters. 

Fig.  3.     The  apical  cavity  is  still  further  developed.     25  diameters. 

Fig.  4.     Beginning  of  the  palisade  layer.     25  diameters. 

Fig.  5.     Further  development  of  the  palisade  layer.     25  diameters. 

Fig.  6.  Maximum  growth  of  the  palisade  layer  in  a  plane  surface.  25  diam- 
eters. 

Fig.  7.  The  palisade  layer  (hymenium  primordium)  produced  into  a  con- 
cave surface  by  the  outward  growth  of  the  edges  of  the  pileus.  25  diameters. 

Fig.  8.  Median  longitudinal  section  through  a  small  sporophore  formed 
upon  the  cut  end  of  a  stipe.  18  diameters. 


[486] 


UNIV.    CALIF.    PUBL.    BOT.    VOL.    7 


[ ESSIG  ]    PLATE    55 


PLATE  56 

Fig.  1.  A  piece  of  wood  removed  from  the  surface  of  an  UmbelJularia  log, 
showing  a  number  of  very  small  sporophores  in  the  earliest  stage  of  development. 
Surface  and  side  views.  2%  diameters. 

Fig.  2.  Shapes  assumed  by  very  young  undifferentiated  fruit  bodies.  2% 
diameters. 

Fig.  3.  A  group  of  young  fruit  bodies  in  position  upon  a  piece  of  Vmbel- 
lularia  bark.  Five  of  the  specimens  are  in  the  "apical  cavity"  stage,  one  is 
still  undifferentiated,  and  another  (at  the  extreme  right)  has  already  developed 
lamellar  plates.  3%  diameters. 

Fig.  4.  Tangential  section  of  Acacia  wood  to  show  the  mycelium  of  Scliizo- 
phyllum  commune  in  a  duct.  About  125  diameters. 

Fig.  5.  Radial  section  of  Umbettularia  wood  to  show  the  hyphae  of  Schizo- 
phyllum  in  the  ducts.  About  125  diameters. 

Fig.  6.  Splitting  of  the  palisade  layer  previous  to  the  formation  of  a 
lamellar  ridge.  250  diameters. 

Fig.  7.  Outward  growth  of  the  palisade  layer  at  the  sides  of  a  split.  250 
diameters. 

Fig.  8.  Loosening  and  outward  growth  of  the  elements  of  the  palisade 
layer  to  form  a  lamellar  ridge.  250  diameters. 

Fig.  9.  Cross-section  of  the  palisade  layer  to  show  a  very  early  stage  in 
the  origin  of  a  lamellar  ridge.  250  diameters. 


[488] 


UNIV.    CALIF.    PUBL.    BOT.    VOL.    7 


[  ESSIG  ]    PLATE    56 


PLATE  57 

Fig.  1.     A  transverse  section  across  a  lamellar  ridge  in  a  very  early  stage 
of  development.     448  diameters. 

Fig.  2.     A  cross-section  through  a  lamellar  ridge  divided  down  in  the  middle 
to  form  two  small  lamellar  plates.    448  diameters. 

•   Fig.  3.     Another  lamellar  ridge  in  a  stage  of  development  similar  to  that 
shown  in  fig.  2.     448  diameters. 

Fig.  4.     A  lamellar  ridge  whose  halves  are  split  apart  deeply  into  the  pilens 
flesh.     448  diameters. 


[490] 


UNIV.    CALIF.    PUBL.    BOT.    VOL.    7 


[  ESSIG  ]    PLATE    57 


4 


PLATE  58 

Fig.  1.  Sections  of  apple  limbs  with  the  wood  rotted  by  fungi  penetrating 
through  an  improperly  sealed  graft.  Sporophores  of  ScTiizopliylluni  appeared 
upon  the  bark  of  the  tree  beneath  the  graft  about  a  year  after  the  grafting 
was  done.  See  the  text  for  further  explanation.  y2  natural  size. 

Fig.  2.  Sporophores  of  Scliizopliyllum  commune  in  a  dry  condition  upon  the 
bark  of  a  living  peach  tree  at  the  side  of  a  crotch  split.  The  lower  end  of  the 
split  can  be  seen  on  the  right  side  of  the  trunk.  %  natural  size. 


[492] 


UNIV.    CALIF.    PUBL.    BOT.    VOL.    7 


;  ESSIG  ]    PLATE    58 


PLATE  59 

Fig.  1.  A  median  longitudinal  section  through  a  very  small  undifferentiated 
fruit  body.  See  fig.  1,  pi.  54.  55  diameters. 

Fig.  2.  A  median  longitudinal  section  of  a  sporophore  showing  the  breaking 
in  of  the  apical  cavity.  55  diameters. 

Fig.  3.     Photomicrograph  of  the  section  drawn  in  fig.  6,  pi.  54.     55  diameters. 

Fig.  4.  A  median  longitudinal  section  through  a  fruit  body  with  the  apical 
cavity  fully  developed.  55  diameters. 


[494] 


UNIV.    CALIF.    PUBL.    BOT.    VOL.    7 


[  ESSIG  ]    PLATE    59 


•at 


PLATE  60 

Fig.  1.  A  widened  lamellar  ridge  in  cross-section,  showing  the  sterile  area 
between  the  edges  of  the  hymenium.  75  diameters. 

Fig.  2.  A  sporophore  developed  from  a  single  lobe  of  a  mutilated  inverted 
specimen.  For  a  further  description  see  the  text.  2  diameters. 

Fig.  3.  A  median  longitudinal  section  through  a  regenerated  sporophore. 
See  text  for  further  explanation.  75  diameters. 


[496] 


UNIV.    CALIF.    PUBL.    EOT.    VOL.    7 


ESSIG  ]    PLATE    60 


1 


PLATE  61 

A  radial  section  through  Umbellularia  wood  with  the  hyphae  of  Schizophyllum 
commune  in  the  tracheae.    350  diameters. 


[498] 


UNIV.    CALIF.    PUBL.    BOT.    VOL.    7 


[  ESSIG  J    PLATE    61 


UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS— (Continued) 

Vol.  6.     1914-1919. 

1.  Parasitic  Florideae,  by  William  Albert  Setchell.     Pp.  1-34,   plates  1-6. 

April,  1914 _ _ 35 

2.  Phytomorula  regularis,  a  Symmetrical  Protophyte  Related  to  Coelastmm,  by 

Charles  Atwood  Kofold.    Pp.  35-40,  plate  7.    April,  1914 06 

3.  Variation  In  Oenottiera  ovata,  by  Katherine  Layne  Brandegea.    Pp.  41-50, 

plates  8-9.    June,  1914  10 

4.  Plantae  Mexicanae  Purpuslanae.    VI,  by  Townshend  Stith  Brandegee.    Pp. 

51-77.    July,  1914 _ 26 

5.  The  Scinaia  Assemblage,  by  William  Albert  Setchell.     Pp.  79-152,  plates 

10-16.     October,  1914  _ 75 

6.  Notes  on  Pacific  Coast  Algae.    I,  Pylaiella  Postdsiae,  n.  sp.,  a  New  Type  In 

the  Genus  PylaieUa,  by  Carl  Skottsberg.    Pp.  153-164,  plates  17-19.    May, 

1915  _ 15 

7.  New  and  Noteworthy  Calif ornlan  Plants.    II,  by  Harvey  Monroe  Hall    Pp. 

165-176,  plate  20.    October,  1915 _.._ 15 

8.  Plantae  Mexicanae  Purpusianae.  VII,  by  Townshend  Stlth  Brandegee.    Pp. 

177-197.     October,  1915  _ _ _ 26 

9.  Floral  Relations  among  the  Galapagos  Islands,  by  A.  L.  Kroeber.      Pp. 

199-220.    March,  1916 „ 20 

10.  The  Comparative  Histology  of  Certain  Californian  Boletaceae,  by  Harry  S. 

Tates.    Pp.  221-274,  plates  21-25.    February,  1916 50 

11.  A  Revision  of  the  Tuberales  of  California,  by  Helen  Margaret  Gilkey.    Pp. 

275-356,  plates  26-30.    March,  1916  _ „ _ 80 

12.  Species  Novae  vel  Minus  Cognitae,  by  T.  S.  Brandegee.    Pp.  357-361.    May, 

1916  „ _ „ 05 

13.  Plantae  Mexicanae  Purpusianae.    VIII,  by  Townshend  Stlth  Brandegee. 

Pp.  263-375.    March,  1917  ...„ _ _ 15 

14.  New  Pacific  Coast  Marine  Algae.    I,  by  Nathaniel  Lyon  Gardner.    Pp.  377- 

416,  plates  31-35.    June,  1917  _ .40 

15.  An  Account  of  the  Mode  of  Foliar  Abscission  in  Citrus,  by  Robert  W. 

Hodgson.    Pp.  417-428,  3  text  figures.    February,  1918 10 

16.  New  Pacific  Coast  Marine  Algae.    II,  by  Nathaniel  Lyon  Gardner.    Pp.  429- 

454,  plates  36-37.    July,  1918  25 

17.  New  Pacific  Coast  Marine  Algae,    m,  by  Nathaniel  Lyon  Gardner.    Pp. 

455-486,  plates  38-41.    December,  1918 35 

18.  New  Pacific  Coast  Marine  Algae.    IV,  by  Nathaniel  Lyon  Gardner.    Pp. 

487-496,  plate  42.    January,  1919 _ _      .16 

19.  Plantae  Mexicanae  Purpusianae.    IX,  by  Townshend  Stith  Brandegee.    Pp. 

497-504.    November,  1919 _ 05 

Index  in  preparation. 

Vol.  7.    1916-1922. 

1.  Notes  on  the  Californian  Species  of  Trillium  L.    I,  A  Report  of  the  General 

Results  of  Field  and  Garden  Studies,  1911-1916,  by  Thomas  Harper  Good- 
speed  and  Robert  Percy  Brandt.    Pp.  1-24,  plates  1-4.    October,  1916 25 

2.  Notes  on  the  Californian  Species  of  Trillium  L.    n,  The  Nature  and  Occur- 

rence of  Undeveloped  Flowers,  by  Thomas  Harper  Goodspeed  and  Robert 
Percy  Brandt.    Pp.  25-38,  plates  5-6.    October,  1916  _      .15 

3.  Notes  on  the  Californian  Species  of  Trillium  L.    Ill,  Seasonal  Changes  in 

Trillium  Species  with  Special  Reference  to  the  Reproductive  Tissues,  by 
Robert  Percy  Brandt.    Pp.  39-68,  plates  7-10.    December,  1916 30 

4.  Notes  on  the  Californian  Species  of  Trillium  L.    IV,  Teratological  Varia- 

tions of  Trillium  sessile  var.  giganteum  H.  &  A.,  by  Thomas  Harper  Good- 
speed.    Pp.  69-100,  plates  11-17.    January,  1917 _ JO 


UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS— (Continued) 

5.  A  Preliminary  List  of  the  Uredinales  of  California,  by  Walter  C.  Blasdale. 
Pp.  101-157.  August,  1919  _ „ 

6,  7,  8.  A  Rubber  Slant  Survey  of  Western  North  America.  Z  Chrysothamnus 
nauseosus  and  Its  Varieties,  by  Harvey  Monroe  Hall.  II.  Chrysil,  a  New 
Rubber  from  Chrysothamnus  nauseosus,  by  Harvey  Monroe  Hall  and 
Thomas  Harper  Goodspeed.  331.  The  Occurrence  of  Rubber  in  Certain 
West  American  Shrubs,  by  Harvey  Monroe  Hall  and  Thomas  Harper 
Goodspeed.  Pp.  159-278,  plates  18-20,  8  figures  in  text.  November,  1919. 

9.  Phycologlcal  Contributions.  I,  by  William  Albert  Setchell  and  Nathaniel 
Lyon  Gardner.  Pp.  279-324,  plates  21^31.  April,  1920  

10.  Plantae  Mexicanae  Purpusianae.    X,  by  Townshend  Stith  Brandegee.    Pp. 

325-331.     December,  1920  ..._ _ 

11.  Phycological  Contributions  II  to  VI.     New  Species  of:  II.  Myrionema; 

III.  Compsonema;  IV.  Hecatonema;  V.  Pylaiella  and  Streblonema;  VI. 
Ectocarpus.  By  William  Albert  Setchell  and  Nathaniel  Lyon  Gardner. 
Pp.  333-426,  plates  32-49.  May,  1922 _. 

12.  Notes  on  Pacific  Coast  Algae.    II.  On  the  Calif ornlan  "Delesseria  Querci- 

folia,"  by  Carl  Skottsberg.    Pp.  427-436,  plate  50.    June,  1922 

13.  Undescribed  plants  mostly  from  Baja  California,  by  Ivan  Murray  Johnston. 

Pp.  437-446.    August,  1922 

14.  Morphology,  Development,  and  Economic  Aspects  of  Schizopltyllum  com- 

mune  Fries,   by  Frederick  Monroe   Essig.     Pp.   447^98,   plates   51-61. 

August,  1922 

Index  in  preparation. 

VcL  8.     1919-. 

1.  The  Marine   Algae   of  the   Pacific   Coast   of   North   America.     Part   L 

Myxophyceae,  by  William  Albert  Setchell  and  Nathaniel  Lyon  Gardner. 
Pp.  1-138,  plates  1-8.  November,  1919 _ „ : 

2.  The  Marine  Algae  of  the  Pacific  Coast  of  North  America.     Part  II. 

Chlorophyceae,  by  William  Albert  Setchell  and  Nathaniel  Lyon  Gardner. 
Pp.  139-374,  plates  9-33.  July,  1920  „ 

Vol.  9.    A  Report  upon  the  Boreal  Flora  of  the  Sierra  Nevada  of  California,  by  Frank 
Jason  Smiley.    Pp.  1-423,  plates  1-7.    October,  1921 

Vol.  10.     1922-. 

1.  The  Genus  Fitcvs  on  the  Pacific  Coast  of  North  America,  by  Nathaniel  Lyon 
Gardner.  Pp.  1-180,  plates  1-60.  April,  1922 

Vol.  11.     1922-. 

1.  Interspecific  Hybridization  in  Nicotiaiia.  I.  On  the  Results  of  Backcrossing 
the  F,  Syh'estris-Talaeum  Hybrids  to  Sylventris,  by  Thomas  Harper  Good- 
speed  and  Roy  Elwood  Clausen.  Pp.  1-30.  August,  1922 


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